KICP in the News

Prof. Michael Turner's May 5 lecture at Adler Planetarium to be simulcast nationally
UChicago News, May 5, 2016
Prof. Michael Turner, Director of the PFC and KICP
Prof. Michael Turner, Director of the PFC and KICP
by Steve Koppes, UChicago News

Prof. Michael Turner will explore some of the biggest mysteries of modern cosmology in a 7:30 p.m. May 5 lecture at the Adler Planetarium. The cosmologist’s Kavli Fulldome Lecture, titled "From the Big Bang to the Multiverse and Beyond," will be streamed live at 15 other institutions across North America.

Kavli Fulldome Lecture
Is the universe part of a larger multiverse? What is speeding up the expansion of the universe? Turner will address these and other mysteries that inspire modern cosmologists. His talk will stream live simultaneously at 15 other institutions across North America. This dome-cast will allow audiences across North America to immerse themselves in the live presentation and ask questions, and will include institutions like the American Museum of Natural History in New York City, the Pacific Science Center in Seattle and the H.R. MacMillan Space Centre in Vancouver, British Columbia.

A theoretical astrophysicist, Turner is the Bruce V. and Diana M. Rauner Distinguished Service Professor and director of its Kavli Institute for Cosmological Physics. Turner helped to pioneer the interdisciplinary field of particle astrophysics and cosmology. He has made seminal contributions to the current cosmological paradigm known as LambdaCDM, including the prediction of cosmic acceleration. Turner has received numerous prizes and is a member of the National Academy of Sciences.

Current list of institutions participating in the dome-cast:

  • American Museum of Natural History, New York City.
  • Denver Museum of Nature and Science, Denver.
  • Pacific Science Center, Seattle.
  • Cradle of Aviation Museum, Garden City, N.Y.
  • Minnesota State University Moorhead, Moorhead, Minn.
  • Gary E. Sampson Planetarium, Wauwatosa, Wis.
  • Casper Planetarium, Casper, Wyo.
  • Bell Museum of Natural History, Minneapolis.
  • Peoria Riverfront Museum, Peoria, Ill.
  • H.R. MacMillan Space Centre, Vancouver, B.C.
  • The Journey Museum and Learning Center, Rapid City, S.D.
  • Aldo Leopold Nature Center, Madison, Wis.
  • Marshall W. Alworth Planetarium, University of Minnesota Duluth.
  • Jackson Middle School Observatory, Champlin, Minn.
  • Planetarium and Visualization Theater, University of Alaska, Anchorage.


Related Links:
KICP Members: Michael S. Turner
Physics in your future: Brittany Kamai
APS, Women in Physics, May 2, 2016
Brittany Kamai, KICP graduate student
Brittany Kamai, KICP graduate student
APS, Women in Physics

When Brittany Kamai took her first astronomy class as a freshman at the University of Hawaii, her professor told her that we can only see about 4% of the stuff in the universe. The rest is made of mysterious substances called dark matter and dark energy. "I found it fascinating that in the entire textbook for our class, there was barely a paragraph about this crazy thing," she recalls. Inspired, Brittany decided to study physics. During the summer before her last year of college, she accepted an opportunity to do research at the Institute for Astronomy at the University of Hawaii. She was hooked. Brittany went on to join the Fisk-Vanderbilt Master's-to-PhD Bridge Program, a two-year program designed to help students with limited undergraduate research experience. She is now in the PhD program at Vanderbilt University in Tennessee. But she actually spends most of her time in Chicago, because her research is based at Fermilab, a large U.S. Department of Energy research facility in northern Illinois. Brittany is building what she calls "the world's most precise ruler" - also called a "holometer." She and her colleagues hope to use intersecting laser beams to measure space itself very precisely, so they can look for tiny differences between what they measure and what Einstein's theory of general relativity predicts about it. Brittany and her colleagues are now testing the machine and making it as accurate as possible. They have just begun to run their experiment and hope to have results very soon. She will soon finish graduate school, but plans to continue pursuing experimental research in astrophysics. She likes the variety of work she gets to do. "Sometimes it's nice to say OK, I don't have to go into the lab, I can be behind my computer," she says. "And sometimes it's like, I'm sick of this - let me go back in lab! I enjoy that." When Brittany's not doing science, she's often talking about it, and encouraging young people - especially girls - to pursue it. She sees this as an important part of her job. In the past five years, she has shared her enthusiasm for science at museums, at middle schools and high schools, and even at senior centers. "You talk to people who are 50-plus, they get super-jazzed about it, they tell their kids, their grandkids," she says. "And it's like yes! This is how you get people excited about science."


Related Links:
KICP Members: Stephan S. Meyer
KICP Students: Brittany Kamai
Joshua Frieman elected to American Academy of Arts and Sciences
UChicago News, April 26, 2016
Joshua Frieman elected to American Academy of Arts and Sciences
by Mary Abowd and Steve Koppes, UChicago News

Joshua Frieman is a professor of astronomy & astrophysics and the College. He is also a member of the Kavli Institute for Cosmological Physics at UChicago and a member of the theoretical astrophysics group at Fermi National Accelerator Laboratory. He focuses his research on theoretical and observational cosmology, including studies of the nature of dark energy, the early universe, gravitational lensing, the large-scale structure of the universe and supernovae as cosmological distance indicators.

Frieman is a co-founder and director of the Dark Energy Survey, an international collaboration of more than 300 scientists from 25 institutions on three continents that investigates why the expansion of the universe is accelerating. The collaboration built a 570-megapixel camera for the four-meter Blanco Telescope at the Cerro Tololo Inter-American Observatory in Chile to conduct its observations. Previously Frieman led the Sloan Digital Sky Survey Supernova Survey, which discovered more than 500 type Ia supernovae for cosmological studies.

Frieman is an honorary fellow of the Royal Astronomical Society, and a fellow of the American Physical Society and of the American Association for the Advancement of Science.


Related Links:
KICP Members: Joshua A. Frieman
Scientific projects: Dark Energy Survey (DES)
Experiment probes nature of space and time
UChicago News, April 19, 2016
Photo by Reidar Hahn/Fermi National Laboratory
Photo by Reidar Hahn/Fermi National Laboratory
by Carla Reiter, UChicago News

For the past year at Fermilab, an instrument called the Holometer has been probing the fundamental nature of space. The experiment uses an array of lasers and mirrors to try and answer the question, "If you look at the infinitesimally small scale, is space smooth and unbroken - the way we experience it in everyday life - or is it pixelated like the image on a TV screen?"

Recent initial results are homing in on an answer. Either way, the outcome will have important consequences for physical theory. It may even help address one of the most nagging problems in physics: how to reconcile Einstein's General Theory of Relativity with quantum mechanics.

The Holometer is an anomaly - an experiment in a scientific territory in which there are no other experiments. Craig Hogan, professor of astronomy and physics at UChicago and head of Fermilab's Center for Particle Astrophysics, envisioned the Holometer as a way to probe the zone where quantum mechanics and general relativity might come together.

General relativity describes space-time and gravitation in the large-scale world we inhabit. It makes definite predictions. Quantum mechanics describes the world at the atomic and sub-atomic scale, which is not continuous but granular, or quantized. It deals in probabilities, uncertainties, and there is a limit to the amount of information that can be had about anything being observed. It has other stranger qualities as well, such as the fact that distant parts of a quantum system can be influenced by each other - a phenomenon that Einstein pejoratively dismissed as "spooky action at a distance."

"In a way, for me, this thing has already succeeded exactly as we hoped, because it's guiding theory."
- Prof. Craig Hogan
Head of Fermilab's Center for Particle Astrophysics

The problem is getting from one scale to the other. In the canonical way of doing science, theory makes predictions, experiments test those predictions, and experimental results inform the next iteration of theory. But in the domain of quantum gravity, there is no experimental evidence at all. In fact, there is no real theory - only competing models.

"Many of these ideas are great ideas," says Hogan. "It's just that people don't know which ones apply to reality. And there's no experiment to guide them."

That's where the Holometer comes in. Its mission is to look for "holographic noise" - an effect of quantum uncertainty in our 3D universe. Hogan's idea is that if space itself were quantized at the Planck scale, our apparently continuous space could emerge from it in much the same way that fluid, apparently continuous air emerges from the bouncing around of discrete molecules. But some of the strange quantum behavior should "leak out" from the Planck domain into our large-scale world. And that leakage is what the Holometer is designed to detect. It is exploring and measuring space at the Planck scale - something that has never been done before.

The search for quantum jitter
Measurable holographic noise could take a couple of different forms - quantum jitter or purely rotational quantum twists of space. Recently, the Holometer definitively eliminated the first possibility: There is no quantum jitter in space. News media around the world reported that the finding means there is "no evidence that the universe is a hologram," but Hogan says the work's broader significance is the window it opens into phenomena at the Planck scale.

"That's an important result," Hogan says. "It sets a limit on something nature could have been doing. The other part of the news is that we have this technique now that works."

The technique involves a version of a tool used in physics since 1887: a Michelson interferometer, named for the former UChicago physicist and Nobel laureate Albert A. Michelson. Actually, the experiment isn’t one interferometer but two identical instruments set close together. Each comprises two perpendicular 40-meter arms, each with a mirror at the end, that intersect at a beam-splitting mirror. Laser light sent through the beam splitter splits, half going down one arm and half down the other. Both beams are reflected back through the beam splitter, where they recombine, or interfere.

If there had been a quantum jitter in space at the Planck scale, the relative positions of the mirrors would have shifted ever so slightly, and the jitter would have shown up as a tiny offset in the interference pattern.

Using two instruments that share the same slice of space-time makes it possible for the scientists to exploit the quantum mechanical phenomenon of correlation to help them tease out any sign of jitter. "If you have two interferometers next to each other, the space in one is correlated with the other," says Hogan. "So if one moves, the other moves with it even if there's no physical connection." The two instruments are shielded from ambient sources of jiggle and isolated from one another so that no light can move between them.

"They really had to be independent systems," says Stephan Meyer, professor in astronomy and astrophysics and physics who designed most of the Holometer's electronic and mechanical systems. "If you have two devices and all of the jiggling that they would normally do is not related, you can use a mathematical technique that sniffs out the part where they move together."


Related Links:
KICP Members: Craig J. Hogan; Stephan S. Meyer
Cosmic Speed Measurement Suggests Dark Energy Mystery
Scientific American, April 17, 2016
Daniel Scolnic, KICP Fellow
Daniel Scolnic, KICP Fellow
by Clara Moskowitz, Scientific American

The Hubble constant measurement from the early universe, on the other hand, comes from observations of the cosmic microwave background (CMB) light that is left over from the big bang and pervades the entire sky. Researchers studied patterns in the CMB and extrapolated to modern times, based on the best known cosmological laws, to arrive at the Hubble constant. The best observations to date of the CMB were made by the European Space Agency's Planck satellite, whose data puts the universe's expansion rate at 67.3, plus or minus 0.7, kilometers per second per megaparsec.

"Before, there were these hints of tension in the two measurements," says Dan Scolnic of the University of Chicago, a member of Riess' team. "Now both our team and the Planck team have reanalyzed and those hints have become something stronger. We have this alarm bell that there really could be something more going on. This may be the biggest tension now in cosmology."

The latest result is also in good agreement with other measurements of the Hubble constant based on similar distance ladder measurements, such as a 2012 study led by Wendy Freedman of the University of Chicago. "I think it's interesting that they’ve increased their sample size and the result is essentially unchanged," Freedman says. "This is spectacular progress to be at this point, but actually making a definitive measurement at this level requires independent methods. How this will ultimately resolve is really too early to say." Freedman is leading an effort to perform the same calculation using another type of cosmic yardstick - RR Lyrae variable stars - in place of Cepheids.


Related Links:
KICP Members: Wendy L. Freedman; Daniel Scolnic
Prof. Wendy Freedman suggests standard model of measuring speed of universe's expansion may be incorrect
Nature, April 14, 2016
by Davide Castelvecchi, Nature

Another possibility is that standard candles themselves that are not reliable when it comes to precision measurements, says Wendy Freedman, an astronomer at the University of Chicago in Illinois who in 2001 led the first precision measurement of the Hubble constant3. She and her team are working on an alternative method based on a different class of stars.


Related Links:
KICP Members: Wendy L. Freedman
526th Convocation Address: John Carlstrom - "Our Expanding View Of The Universe"
The University of Chicago, April 14, 2016
John E. Carlstrom, Deputy Director of the PFC and the KICP
John E. Carlstrom, Deputy Director of the PFC and the KICP
The University of Chicago

The University Ceremony of the 526th Convocation of the University of Chicago was held on March 18, 2016, in Rockefeller Memorial Chapel. Provost Eric D. Isaacs introduced Subrahmanyan Chandrasekhar Distinguished Service Professor, Professor in the Departments Of Astronomy & Astrophysics and Physics, Enrico Fermi Institute, and the College John Carlstrom, who delivered the Convocation Address, "Our Expanding View Of The Universe."


Related Links:
KICP Members: John E. Carlstrom
Michael Turner discusses LIGO & the detection of gravity waves
STEM-Talk, April 12, 2016
Michael Turner discusses LIGO & the detection of gravity waves

Michael Turner is best known for having coined the term "dark energy" in 1998. A theoretical cosmologist at the University of Chicago, Turner has dedicated his career to researching the Big Bang, dark energy and dark matter. He wrote his Ph.D. thesis on gravitational waves - back in 1978 - and nearly four decades later had a bird's eye view of their recent discovery. Turner was assistant director of the National Science Foundation (NSF), which funded the development of LIGO, which stand for the Laser Interferometer Gravitational-Wave Observatory. This large-scale physics experiment and observatory, which was led by researchers at MIT and CalTech, discovered, on September 15th, 2015, the existence of gravitational waves via a chirping noise signaling the collision of two black holes a billion light-years away. The scientists announced their discovery on February 11th, 2016. In this episode, Turner interprets this momentous finding, and talks about some of the big player scientists who worked on LIGO.


Related Links:
KICP Members: Michael S. Turner
TCN Panel on Space: Wendy Freedman and Angela Olinto
The Chicago Network, April 1, 2016
TCN Panel on Space: Wendy Freedman and Angela Olinto
The Chicago Network

If you can't see it, you won't be it. Future women leaders need examples.

In that spirit, The Chicago Network recently gathered an audience of young women and Network members to hear from four of the world’s foremost astrophysicists - all Network members - to demonstrate the tremendous impact women are making in STEM and the possibilities that lie ahead for the next generation. Young scientists left feeling energized by the program moderated by Adler Planetarium President and CEO Michelle Larson, and ready to take on the challenge of studying even the most profound universal mysteries.

According to Michelle, panelists Wendy Freedman, Vicky Kalogera, and Angela Olinto illustrate more than an exploration of the universe in this program, they demonstrate what it is to discover your own individual capacity for leadership:

The panelists in this program take us on a journey through the Universe, and provide inspiration through their life stories. You will hear about measuring the age and size of the Universe, probing current mysteries like dark energy and dark matter, and opening a new observational era with the discovery of gravitational waves. As you take this journey, also listen for the words passion, people, and perseverance - all play an important role in their success. Finally, listen for the number of times you hear these women say "I led" or "I lead." These panelists are amazing leaders, and each of them is certain you could be too. What a great endorsement of your potential - run with it!
- Michelle Larson, President and CEO, Adler Planetarium


Related Links:
KICP Members: Wendy L. Freedman; Angela V. Olinto
Scientific projects: Giant Magellan Telescope (GMT); Pierre Auger Observatory (AUGER)
Young women learn that not even sky is limit in STEM careers
Chicago Tribune, February 24, 2016
(From left) Michelle Larson, president & CEO, Adler Planetarium; moderated the panel of speakers including Vicky Kalogera, E.O, Haven professor of physics & astronomy, Northwestern University; Wendy Freedman, professor of astronomy and astrophysics, University of Chicago and KICP senior member; and Angela Olinto, Homer J. Livingston professor, University of Chicago and KICP senior member
(From left) Michelle Larson, president & CEO, Adler Planetarium; moderated the panel of speakers including Vicky Kalogera, E.O, Haven professor of physics & astronomy, Northwestern University; Wendy Freedman, professor of astronomy and astrophysics, University of Chicago and KICP senior member; and Angela Olinto, Homer J. Livingston professor, University of Chicago and KICP senior member
by Lori Janjigian, Chicago Tribune

Fighting roadblocks is key for women who want to reach success in STEM fields, panelists said Monday at The Chicago Network's Panel on Space.

"We all run into difficulties, but with guys, something is wrong with the test or with the professor or something else, but women internalize it. They say 'I can't do it,'" said Wendy Freedman, an astronomy professor at the University of Chicago.

Freedman was a principal investigator on the Hubble Space Telescope Key Project and also founding chairman of the Giant Magellan Telescope Organization, dedicated to building a massive telescope to see 20 million times what a human eye can.

Freedman was one of three panelists who spoke to an audience of 150 Girls Scouts, other middle- and high school-age girls, and members of The Chicago Network.

"I remember a high school teacher of mine once said, 'This is too technical, the girls don't have to listen,'" Freedman said. "At university, someone told me that girls belong in the kitchen. We all run into difficulties, but don't give up. Perseverance is critical."

Freedman was joined by Northwestern University's Vicky Kalogera and the University of Chicago's Angela Olinto. The three women spoke about overcoming difficulties as well as the science they've been working on.

"To have the opportunity to share this with the younger generation is important. I know peer pressure is intense to move girls away from science and math, and I know there are not a lot of role models," Kalogera said. "It would have been amazing for me, when I was young, to meet a grown-up scientist and to have a discussion with them and hear from them."

Kalogera is an astrophysicist who worked on the recent discovery of gravitational waves in the universe, which confirmed part of Einstein's Theory of Relativity. She is interested in the interaction of compact objects within binary systems, in which two stars orbit each other. She also is the director of the Center for Interdisciplinary Exploration and Research in Astrophysics at Northwestern.

Kalogera told students about her work in astrophysics in addition to discussing the difficulties she has faced along the way, from receiving a 60 percent on her first test in college to trying to balance being a mother of two and working on her career today.

Angela Olinto studies ultra-high-energy cosmic rays, which aren't well-understood. To study these rays, Olinto is leading the U.S. collaboration to send a cosmic ray telescope to the International Space Station. The project, however, has faced many roadblocks.

"We have the device; we just need a ride there," Olinto said.

She encouraged the young women in the audience to diversify their lives, because other smaller tasks help get you through the day: "I do a lot more than just build telescopes," Olinto said, who also has a passion for music and is a professor at the University of Chicago.

The panel, moderated by Michelle Larson, CEO of Adler Planetarium, provided examples of what women could do with a STEM education.

"Our girls have big dreams about the future, but are unsure about what is out there for them," said Karissa Dewey, troop leader of the Highland Middle School Girl Scouts of Highland, Ind. "Bringing them into the city and introducing them to women in science and technology, they were absolutely floored."


Related Links:
KICP Members: Wendy L. Freedman; Angela V. Olinto
Scientific projects: Giant Magellan Telescope (GMT)
Gravitational Waves Discovery Confirms Einstein's Theory
Here and Now, February 19, 2016
Merging black holes ripple space and time in this artist’s concept. Pulsar-timing arrays - networks of the pulsing cores of dead stars - are one strategy for detecting these ripples, or gravitational waves, thought to be generated when two supermassive black holes merge into one. (Image credit: Swinburne Astronomy Productions via NASA Jet Propulsion Lab)
Merging black holes ripple space and time in this artist’s concept. Pulsar-timing arrays - networks of the pulsing cores of dead stars - are one strategy for detecting these ripples, or gravitational waves, thought to be generated when two supermassive black holes merge into one. (Image credit: Swinburne Astronomy Productions via NASA Jet Propulsion Lab)
Here and Now

Einstein was right: gravitational waves do exist. Scientists confirmed Einstein's theory with the groundbreaking discovery, announced today at the National Press Club, that gravitational waves were detected after a collision of a pair of unusual black holes.

Michael Turner, a professor of astronomy and astrophysics and director of the Kavli Institute for Cosmological Physics at the University of Chicago, speaks with Here & Now's Jeremy Hobson about what this discovery tells us about our understanding of the universe.

Interview Highlights: Michael Turner

What exactly did scientists discover here?
"I would call this a Galileo moment. The big news today is that 1.3 billion years ago, in a galaxy far, far away, two black holes collided and coalesced to form one black hole, and they twisted and bent and roiled and contorted space-time and that started a ripple, a really big ripple. You would not have wanted to be in that ripple. That ripple traveled 1.3 billion light years to us and it was detected by the gravitational wave detectors in Livingston, Louisiana and in Hanford, Washington that were built by the NSF back in 1992."

On the detection centers in Louisiana and Washington
"This ripple in space-time causes the distance between the end points of the gravitational wave detector, which are four kilometers apart, to change by less than a thousandth the size of the proton."

Which means?
"10-16 centimeters, if you really want it. But it's amazing that human beings can build instruments to do that, and in this new way we look at the universe, the brightest things, and the things that are the easiest to see, are really exotic things."

Give us a sense of what this means for our understanding of the universe. How do we feel today versus yesterday about what's around us?
"I think number one is, Einstein's theory passed the last major test. That's a big one. These are black holes. In general relativity these are the simplest objects; they have the strongest fields and, I'm going to use a slightly technical term here, the waveform that was detected. When you plot the results, they look and see if the waveform agrees with what Einstein’s theory says for two black holes coming together, and it does. So this is a big boost to our understanding of black holes, and then of course I think the final really big one that’s so amazing is that advanced LIGO, they will have earned their 'O.' So Laser Interferometer Gravitational-Wave Observatory, so they’re going to be seeing tens of events per year."

So now that we can observe these waves, we can learn much more about them?
"That's right. So the rest of the year there are going to be 10 more events, some of them will be black holes coalescing, some of them will be a black hole leading a neutron star, and the ones that every scientist is so excited about are the surprises, where you go 'Oh my god, what is that? We never calculated that. What's that thing?' So it's the surprises and every time we've turned our eyes on the universe with a new kind of instrument, x-rays or microwaves, the most important discovery is not the one we said, 'Oh yeah, we're gonna do this one for sure,' it's the big surprise. People are very excited for what surprises lie ahead."

Is this the most exciting moment of your scientific career?
"I've been very lucky. Dark matter, dark energy, inflation, this has just been a very exciting time in our understanding of the universe. I have to tell you about a meeting that took place, I spoke at it, in 1965. Before 1965 you could have said, 'Oh, we live in a pretty boring universe. We've got these ordinary starts and this and that.' 1965 is kind of when this revolution began, the discovery of the microwave background that told us about the Big Bang. The discovery of quasars, which turned out to be objects powered by black holes followed by neutron stars. We live in this amazing universe in which stars like our sun are very ordinary and we have all these exotic objects that we're studying and inspiring the next generation of scientists with."


Related Links:
KICP Members: Michael S. Turner
Scientists find ripples in fabric of spacetime
The University of Chicago News Office, February 11, 2016
KICP graduate students Zoheyr Doctor and Hsin-Yu Chen; KICP senior member Daniel Holz; and KICP associate fellow Ben Farr.
KICP graduate students Zoheyr Doctor and Hsin-Yu Chen; KICP senior member Daniel Holz; and KICP associate fellow Ben Farr.
by By Jeremy Manier and Steve Koppes, The University of Chicago News Office

UChicago physicists say discovery of gravitational waves opens new universe of possibilities

Early on the morning of Sept. 14, 2015, two detectors separated by about 1,800 miles made the first observation of ripples in the fabric of spacetime, ushering in an entirely new way of studying the universe.

The discovery of gravitational waves by the Laser Interferometer Gravitational-Wave Observatory, announced in Washington, D.C. on Feb. 11 by leaders of the international collaboration, fulfills a century-old scientific quest. Albert Einstein's 1915 theory of general relativity predicted that cataclysmic cosmic events would produce gravitational waves that could be detected from Earth.

University of Chicago physicists played an important role in determining that the LIGO detectors had detected gravitational waves from the merger of two black holes, which collided to form a more massive, spinning black hole. Three UChicago physicists are among the many co-authors of the study detailing the discovery, which has been accepted for publication in the journal Physical Review Letters.

"We've been dreaming about this for a long time. It's our first time ever seeing something like this, and it truly opens up a new chapter in physics."
-Daniel Holz
Associate professor in physics and LIGO collaborator

For scientists at UChicago, the finding speaks powerfully to their field's past and its exciting future.

"We've been dreaming about this for a long time," said LIGO collaborator Daniel Holz, associate professor in physics. "It's our first time ever seeing something like this, and it truly opens up a new chapter in physics. You don’t get to do that very often."

In addition to providing the first observation of ripples in spacetime, the discovery is a dramatic confirmation that black holes are real, Holz said. "The physics community was convinced, but we've never seen one up close," he said. "Now we're going right to the heart of these objects, from a billion light years away. These measurements leave little doubt that black holes exist."

Legendary UChicago physicist Subrahmanyan Chandrasekhar was the first to propose in 1930 that massive stars might collapse into objects like black holes - an idea that prominent physicists initially ridiculed. As important as it is to validate the theories of Einstein and Chandrasekhar, the LIGO findings do much more than that, said Edward "Rocky" Kolb, dean of UChicago's Physical Sciences Division.

"This opens up a new window into the universe, to understand the most violent events that happen," Kolb said. "We're in a great position at the University of Chicago to exploit this new opportunity. Using instruments like the Magellan Telescopes in Chile and the future Giant Magellan Telescope, in which UChicago is a founding partner, we will try to see the fireworks that should accompany what we've just heard through gravitational waves."

'Mind-blowingly extreme' cosmic events
Holz’s UChicago collaborators on the LIGO project are Ben Farr, a McCormick Fellow in the Enrico Fermi Institute, and graduate students Hsin-Yu Chen and Zoheyr Doctor. Together, they played a significant role in analyzing the signals to help characterize the source of the gravitational waves, which cause ripples in the fabric of spacetime. LIGO detects this warping of space using laser interferometers, which are sensitive to minute changes in the length of the cavities that the lasers travel through.

"The detector tells you when it sees wiggles - the two detectors, although separated by thousands of miles, wiggle in a predictable way at almost the same time," Holz said. "That tells you there must have been a gravitational wave event. Then you try to understand what produced the wiggles."

The Sept. 14 event was so intense that in the moment before the colliding black holes swallowed each other, they emitted more energy than the entire rest of the universe combined. By studying the LIGO data over a period of months, Holz's team contributed to the international effort to calculate the properties of the black hole collision, such as the mass of the black holes, how far away they are and where they happened in the sky.

Holz previously had written papers suggesting that LIGO analysts should be on the lookout for collisions of two black holes, since they should produce waves strong enough and frequently enough to be observed on Earth. The scale of the cosmic smash-up that LIGO observed is almost unimaginable, Holz said.

"Most black holes have masses in the range of our sun, but these two are significantly more massive," Holz said. "Each black hole compresses 30 suns into an object that's about one hundred miles across, and they crash into each other at almost the speed of light. It's just mind-blowingly extreme."

The team also has played a key role in testing how well the colliding black holes match what relativity theory predicts.

"Does this agree with the predictions of Einstein or are there some little differences? We're trying to help address that question," Holz said. "The short answer is that our observations agree perfectly with Einstein's theory, which is quite remarkable."

For the UChicago team, the feeling post-discovery is almost bittersweet, Holz said, because "there's an awareness that it's such a unique moment. It's so thrilling, so intense, so revolutionary."

Yet collaborators are excited about the next phase of discovery. With continuing upgrades to the detectors' sensitivity, the detection of gravitational waves should become commonplace.

"This is a completely new way of doing astronomy," Holz said. "Traditional telescopes enhance our sight, but gravitational waves are a lot like sound - a sound that actually ripples through spacetime. Up until now, we've been deaf to the universe. Now we're hearing it for the first time."


Related Links:
KICP Members: Ben Farr; Daniel E. Holz; Edward W. Kolb
KICP Students: Hsin-Yu Chen; Zoheyr Doctor
Chicago Scientists Prepare Ultra-Sensitive Camera for South Pole Telescope
Chicago Tonight, February 4, 2016
A detector array fabricated by the Argonne National Laboratory for the SPT-3G camera. Each 3-mm diameter antenna is connected to six superconducting detectors that measure frequencies from the cosmic microwave background. (Reidar Hahn)
A detector array fabricated by the Argonne National Laboratory for the SPT-3G camera. Each 3-mm diameter antenna is connected to six superconducting detectors that measure frequencies from the cosmic microwave background. (Reidar Hahn)
by Evan Garcia, Chicago Tonight

Scientists at the University of Chicago are hoping a new, highly sensitive camera they're developing for the South Pole Telescope will unravel mysteries of our early universe.

The telescope is the largest in Antarctica (it's nearly 33 feet in diameter) and was completed in 2007. The new camera will be the telescope's third and it’ll be a significant upgrade from its predecessor, but more on that later.

Exploring the Cosmos
This isn't the same kind of telescope you might use to observe constellations or planets in the night sky. The South Pole Telescope's purpose is to observe and measure radiation left over from the Big Bang.

Following the logic of the Big Bang theory, the universe began in a hot, dense state far different from the sea of stars and galaxies we see today. Instead, the universe was a primordial soup of high-energy radiation and particles. Over time, the universe cooled and expanded, allowing atoms to form from particles and letting electromagnetic radiation fill the universe as light. From here, about 380,000 years after the Big Bang, this radiation - known as the cosmic microwave background (CMB) – spread throughout the universe while the matter, under the force of gravity, began to form structures that led to the galaxies we see today.

The South Pole Telescope's camera measures this radiation, which contains the earliest imprints of our universe and dates back nearly 14 billion years, making it the oldest light in the universe. Through observation, scientists are hoping to better determine how the universe evolved from the period immediately after the Big Bang to present day. Data may also suggest how the universe will continue to develop. But the CMB's light is very faint and dispersed, so it requires an extra-sensitive camera.

The University of Chicago is working closely with Argonne National Laboratory and Fermilab, along with scientists from over 20 institutions, to construct and eventually install the new camera, SPT-3G, which is four times heavier than the camera it will replace. It also contains 10 times as many superconducting detectors, which are sensitive to the photons of light emitted from the CMB.

These extra-thin detectors are not commercially available, so Argonne is delicately fabricating them at their Center for Nanoscale Materials. It's a process rife with challenges, as University of Chicago astrophysicist John Carlstrom explains.

"The signals we're looking at are so weak," said Carlstrom, who leads the South Pole Telescope Project. "So we have to make sure the detectors are super quiet or noise generated by them will throw us off."

Carlstrom says there are no cameras in the field today with more than one or two thousand detectors - theirs will contain 16,000. If everything goes as planned, the only noise that should interfere with the camera's measurements will be from the sky.


Related Links:
KICP Members: John E. Carlstrom; Clarence L. Chang
Scientific projects: South Pole Telescope (SPT)
South Pole's next generation of discovery
The University of Chicago News Office, January 27, 2016
<i>Image credit:</i> Jason Gallicchio
Image credit: Jason Gallicchio
by Carla Reiter, The University of Chicago News Office

Later this year, during what passes for summer in Antarctica, a group of Chicago scientists will arrive at the Amundsen-Scott South Pole research station to install a new and enhanced instrument designed to plumb the earliest history of the cosmos.

It will have taken the combined efforts of scientists, engineers, instrument builders, and computer experts at UChicago, Argonne National Laboratory, Fermilab, as well as institutions across the world that participate in the South Pole Telescope collaboration.

"It's a really technically challenging scientific project," says Fermilab Director Nigel Lockyer, "and you couldn't do it without the national labs' expertise and enabling technical infrastructure."

Led by John Carlstrom, the S. Chandrasekhar Distinguished Service Professor in Astronomy and Astrophysics, the South Pole Telescope is a global collaboration of more than a dozen institutions. It probes the cosmic microwave background -- the radiation that remains from the Big Bang -- for insight into how the universe has evolved and the processes and particles that have participated in that evolution.

"The collaboration lets us do more than what we could ever do otherwise. We've cultivated the ability to have a single group of 20 or 30 people. ... There's a critical mass, intellectually, that emerges from that."
- Clarence Chang
Argonne National Laboratory physicist

"The physics of the early universe was imprinted into patterns in the cosmic microwave background that we can measure," says Clarence Chang, who heads Argonne's part of the project -- the design and fabrication of the detectors. "But it is very faint, so we need a very sensitive camera."

A new ultra-sensitive camera is both the heart of the telescope and the focal point of the collaboration between Argonne, Fermilab, and Chicago.

"UChicago is the scientific lead," says Bradford Benson, an associate scientist and Wilson Fellow at Fermilab who directs the design of the camera and its integration with cryogenics, detectors, and electronics. "Fermilab provides expertise and resources at the integration level: How do we build this thing, package it, and operate it for many years? And Argonne has micro-fabrication resources that aren't available elsewhere."

The South Pole Telescope project is one of multiple collaborations among UChicago, Argonne, and Fermilab scientists. Others include experiments that examine the nature of neutrinos; as well as those including future accelerator science and technology.

Microwave-sensitive camera
The camera on the South Pole Telescope is made of an array of superconducting detectors that are sensitive to the frequencies associated with the CMB. Each requires depositing ultra-thin superconducting materials with dimensions as small as about 10 x 50 microns (50 microns is the approximate width of a human hair). These delicate detectors are built at Argonne, using the state-of-the-art facilities at the Center for Nanoscale Materials and materials developed in the lab's Materials Sciences Division. The new focal plane uses integrated arrays of detectors on 150 mm silicon wafers, with ten of these modules making up the heart of the camera.

"They're actually detecting the photons from 14 billion years ago," Chang says. "They heat up the detectors a tiny bit, and then we measure that heat."

The finished detector array modules go to Fermilab, where they are packaged and connected with the electronics for testing in the lab's Silicon Detector Facility—a thornier task than it sounds. Each module requires thousands of hair-like wires to be connected individually to cable. Fermilab has specialized wire bonders that are accomplish this task, says Benson.

Then the assembly goes to the University of Chicago, where it is tested at a quarter of a degree above absolute zero -- the temperature required for the superconducting detectors to be able to sense the tiny amount of heat from the incoming photons. The test results are then fed back to Argonne for adjustments to be made for the fabrication of the next modules. Ultimately everything winds up back at UChicago, to be integrated into a 2,000-pound camera to ship to the South Pole.

The new camera will have 16,000 detectors -- a major upgrade from the 1,600-detector camera currently on the telescope. The scientists will use the increased sensitivity to search for the signature of primordial gravitational waves that an inflationary universe would have generated early in its history. A detection would probe physics at the enormous energies that existed when the universe was only a fraction of a second old -- complementary to the studies at the energy scales of the Large Hadron Collider.

The new camera also will enable them to obtain precision measurements that will help determine the mass of neutrinos, so-called ghost particles that were created in huge numbers shortly after the university began and which contribute significantly to its evolution.

Instrumentation mass production
Making 16,000 of anything isn't something universities typically do.

"People are often trying to make one device, understand the physics of it, and publish a paper on it," says Benson. "We're trying to build these instruments that are on a much larger scale, and they need to be mass produced. There's not much of a technical staff or infrastructure at a university to maintain something like that on a five or 10-year time scale. Argonne has built up that expertise. And we can plug into that."

Chang, Benson, and Carlstrom have collaborated on the SPT project for more than a decade. They have worked to create as seamless a process as possible so that scientists, postdocs, and students can go back and forth between groups with no bureaucratic barriers. Both Chang and Benson have part-time appointments at the University, which helps.

"The collaboration lets us do more than what we could ever do otherwise," says Chang. "We've cultivated the ability to have a single group of 20 or 30 people. You'll never have a group in a university or at either of the labs that is that big. There's a critical mass, intellectually, that emerges from that. I think that's the biggest thing that we get out of this. And that's something that's hard to find elsewhere, either at other labs or at other universities."

Although the new telescope isn't yet installed at the South Pole, the project partners are already looking ahead to the next, more sensitive telescope.

"A project the size of the fourth-generation South Pole Telescope requires grand collaborations," said Argonne Director Peter Littlewood. "In order to build, install, and operate an instrument with half a million sensors, we are investing in a multi-institution combination of strong project management and state-of-the-art physical infrastructure to create something truly extraordinary for science."


Related Links:
KICP Members: Bradford A. Benson; John E. Carlstrom; Clarence L. Chang; Jason Gallicchio
Scientific projects: South Pole Telescope (SPT)
Chicago Tonight: Katrin Heitmann speaks about 3-D simulations of the evolution of the universe
Chicago Tonight, January 4, 2016
Katrin Heitmann, KICP senior member
Katrin Heitmann, KICP senior member
by Paul Caine and Sean Keenehan, Chicago Tonight

Argonne National Lab Simulation Tracks the Evolution of the Universe

Scientists at Argonne National Laboratory recently ran one of the most complex simulations of the evolution of the universe ever created. The purpose: To try and understand how the universe came to be and, in particular, to understand the mysterious influence of dark energy and dark matter - which makes up some 95 percent of everything - on its development.

The lead scientist on the project, Katrin Heitmann, joins us to talk about the big science being conducted just outside of Chicago.

What is the scientific value of doing the kinds of cosmological simulations that you do?

Katrin Heitmann: "First of all, what we want to understand in cosmology is the evolution of the universe - how it got to where it is today - as well as the make-up of the universe - what's in it. In order to do that we are running very large surveys that basically map out the distribution of galaxies across the sky in a 3-D map. We have a certain understanding about the universe. We have understanding about the initial conditions and we have an understanding of how it evolved and an understanding of its make-up. What we want to do now with these simulations is exactly create this universe in our lab. So we build this model and we put it on a computer and evolve it forward, and now we have created a universe that we can look at and compare it to the real data."


Related Links:
KICP Members: Katrin Heitmann
NASA's Fermi Satellite Kicks Off a Blazar-detecting Bonanza
NASA, December 15, 2015
Black-hole-powered galaxies called blazars are the most common sources detected by NASA's Fermi Gamma-ray Space Telescope. As matter falls toward the supermassive black hole at the galaxy's center, some of it is accelerated outward at nearly the speed of light along jets pointed in opposite directions. When one of the jets happens to be aimed in the direction of Earth, as illustrated here, the galaxy appears especially bright and is classified as a blazar. <i>Credits: M. Weiss/CfA</i>
Black-hole-powered galaxies called blazars are the most common sources detected by NASA's Fermi Gamma-ray Space Telescope. As matter falls toward the supermassive black hole at the galaxy's center, some of it is accelerated outward at nearly the speed of light along jets pointed in opposite directions. When one of the jets happens to be aimed in the direction of Earth, as illustrated here, the galaxy appears especially bright and is classified as a blazar.
Credits: M. Weiss/CfA

A long time ago in a galaxy half the universe away, a flood of high-energy gamma rays began its journey to Earth. When they arrived in April, NASA's Fermi Gamma-ray Space Telescope caught the outburst, which helped two ground-based gamma-ray observatories detect some of the highest-energy light ever seen from a galaxy so distant. The observations provide a surprising look into the environment near a supermassive black hole at the galaxy's center and offer a glimpse into the state of the cosmos 7 billion years ago.

"When we looked at all the data from this event, from gamma rays to radio, we realized the measurements told us something we didn't expect about how the black hole produced this energy," said Jonathan Biteau at the Nuclear Physics Institute of Orsay, France. He led the study of results from the Very Energetic Radiation Imaging Telescope Array System (VERITAS), a gamma-ray telescope in Arizona.

Astronomers had assumed that light at different energies came from regions at different distances from the black hole. Gamma rays, the highest-energy form of light, were thought to be produced closest to the black hole.

"Instead, the multiwavelength picture suggests that light at all wavelengths came from a single region located far away from the power source," Biteau explained. The observations place the area roughly five light-years from the black hole, which is greater than the distance between our sun and the nearest star.

The gamma rays came from a galaxy known as PKS 1441+25, a type of active galaxy called a blazar. Located toward the constellation Boötes, the galaxy is so far away its light takes 7.6 billion years to reach us. At its heart lies a monster black hole with a mass estimated at 70 million times the sun's and a surrounding disk of hot gas and dust. If placed at the center of our solar system, the black hole's event horizon -- the point beyond which nothing can escape -- would extend almost to the orbit of Mars.

As material in the disk falls toward the black hole, some of it forms dual particle jets that blast out of the disk in opposite directions at nearly the speed of light. Blazars are so bright in gamma rays because one jet points almost directly toward us, giving astronomers a view straight into the black hole's dynamic and poorly understood realm.


Related Links:
Scientific projects: Fermi Gamma-ray Space Telescope (Fermi); Very Energetic Radiation Imaging Telescope Array System (VERITAS)
Cosmic Showers - Professor Angela Olinto discusses relics from the early Universe showering down at the speed of light., December 10, 2015
Cosmic Showers - Professor Angela Olinto discusses relics from the early Universe showering down at the speed of light.

An astrophysicist and professor in the Department of Astronomy and Astrophysics at the University of Chicago, Angela V. Olinto works in particular on the strongest cosmic rays. From balloon to balloon, with a little help from laser beams, she has endeavored to simulate what could be seen by the JEM telescope to be installed on the EUSO observatory on the International Space Station, looking down towards the Earth: ultra-high energy cosmic rays revealing themselves through fluorescent showers of particles, possible messengers from the very first moments of the Universe after the Big Bang.


Related Links:
KICP Members: Angela V. Olinto
Pierre Auger Observatory celebrates 15 years of achievements and a new International Agreement with a Symposium
Pierre Auger Observatory, December 10, 2015
Pierre Auger Observatory celebrates 15 years of achievements and a new International Agreement with a Symposium
by AugerPrime Press Release, Pierre Auger Observatory

AugerPrime Symposium

Celebrating 15 years of achievements and signature ceremony of a new International Agreement for the next 10 years

The Pierre Auger Observatory is the world's leading science project for the exploration of cosmic rays. More than 500 scientists from 16 countries have been working together since 1998 in the Province of Mendoza, Argentina, to elucidate the origin and properties of the most energetic particles in the Universe, coming to us from the far reaches of the cosmos. The Pierre Auger Observatory measures gigantic showers of relativistic particles that are the result of collisions between the very rare, highest-energy cosmic rays and atomic nuclei of the atmosphere. Properties of such air showers are used to infer the energy, direction, and mass of the cosmic particles.

Results from the Pierre Auger Observatory have brought new fundamental insights into the origin and nature of highest-energy cosmic rays. One of the most exciting results is the experimental proof that at the highest energies (7 orders of magnitude above that of the proton beams circulating in the CERN's Large Hadron Collider) the cosmic-ray flux decreases much faster than at low energies. Data indicate that, in addition to the propagation effect known as GZK cutoff, this flux suppression may reveal the limiting energy of the most powerful cosmic particle accelerators. An even more detailed measurement of the nature of cosmic particles at the highest energies is crucial to understand the mechanisms responsible for this decrease, and to identify the astrophysical sites violent enough to accelerate particles to such tremendous energies.

The AugerPrime upgrade to the Observatory enhances the 1660 existing surface detectors (water tanks sensitive to Cherenkov light generated by the shower products) with new scintillation detectors, so that electromagnetic and muonic shower particles can be separated more efficiently. This in turn, together with smaller area of buried muon detectors, improves the determination of the mass of the primary cosmic rays, otherwise not directly measurable. Faster and more powerful electronics also facilitates the readout of the new detector components and enhances the overall performance of the Observatory elements.

A symposium, held on November 15-16, 2015 gathers collaborators and science funding agency representatives for the signing of a new international agreement for continued operation of the Pierre Auger Observatory until 2025. This will provide the basis for doubling the present statistics with the upgraded Observatory, and for solving the long-standing puzzle of the origin of the most energetic particles in the Universe.


Related Links:
KICP Members: James W. Cronin; Angela V. Olinto; Paolo Privitera
Controversial experiment sees no evidence that the universe is a hologram
Science Magazine, December 10, 2015
Controversial experiment sees no evidence that the universe is a hologram
Science Magazine

It's a classic underdog story: Working in a disused tunnel with a couple of lasers and a few mirrors, a plucky band of physicists dreamed up a way to test one of the wildest ideas in theoretical physics—a notion from the nearly inscrutable realm of "string theory" that our universe may be like an enormous hologram. However, science doesn't indulge sentimental favorites. After years of probing the fabric of spacetime for a signal of the "holographic principle," researchers at Fermi National Accelerator Laboratory (Fermilab) in Batavia, Illinois, have come up empty, as they will report tomorrow at the lab.

The null result won't surprise many people, as some of the inventors of the principle had complained that the experiment, the $2.5 million Fermilab Holometer, couldn't test it. But Yanbei Chen, a theorist at the California Institute of Technology in Pasadena, says the experiment and its inventor, Fermilab theorist Craig Hogan, deserve some credit for trying. "At least he's making some effort to make an experimental test," Chen says. "I think we should do more of this, and if the string theorists complain that this is not testing what they're doing, well, they can come up with their own tests."

The holographic principle springs from the theoretical study of black holes, spherical regions where gravity is so intense that not even light can escape. Theorists realized that a black hole has an amount of disorder, or entropy, that is proportional to its surface area. As entropy is related to information content, some theorists suggested that an information-area connection might be extended to any properly defined volume of space and time, or spacetime. Thus, crudely speaking, the maximum amount of information contained in a 3D region of space would be proportional its 2D surface area. The universe would then work a bit like a hologram, in which a 2D pattern captures a 3D image.

If true, the principle might guide string theorists in their grand quest to meld the theories of gravity and quantum mechanics. And it would imply, rather astonishingly, that the total amount of information in the observable universe is finite.

In 2009 Hogan dreamed up a way to test the idea. One way the holographic principle might come about, he reasoned, is if coordinates in different directions—up-down, forward-backward, right-left—obey a quantum mechanical uncertainty relationship a bit like the famous Heisenberg uncertainty principle, which states that you cannot simultaneously know both the position and momentum of a particle such as an electron. If so, then it should be impossible to precisely define a 3D position, at least on very small scales of 10-35 meters.

Hogan figured he could spot the effect using L-shaped optical devices known as interferometers, in which laser light is used to measure the relative length of a device's two arms to within a fraction of an atom's width. If it were impossible to exactly define position, then "holographic noise" should cause the output of an interferometer to jiggle at a frequency of millions of cycles per second, he argued. If two interferometers were placed back to back, they would sample distinct volumes of spacetime, and their holographic noise would be uncorrelated. But if they were nestled one inside the other, the interferometers would probe the same volume of spacetime and the holographic noise would be correlated. And if the interferometers were big enough, that correlated holographic noise should be effectively amplified to observable scales.

Now, Hogan, Fermilab experimenter Aaron Chou, and colleagues have done the measurement with interferometers with 39-meter-long arms. Unfortunately for them, they find no evidence of holographic noise. "A correlation that you would attribute to novel physics effects is not seen," says Lee McCuller, a graduate student at the University of Chicago in Illinois, who will present the result in a talk at the lab.

Just what the null result means remains unclear, however. Chen says he has never fully understood neither exactly how the experiment works nor Hogan's theory of how the holographic principle originates. What's really needed is some sort of general analysis of what types of theories the experiment can and cannot test, he says.

For his part, Hogan says that the experiment reached the sensitivity it aimed for, showing that the technique has the potential to make further measurements. "For me, the big news is that we have a technique for measuring spacetime at this level," he says.

In fact, he says, the holometer can be reconfigured to look not for an inherent uncertainty in positions, but rather for a jitter in angular orientation in spacetime—in his view another possible sign of holographic noise. Maybe the underdogs still have a chance, after all.


Related Links:
KICP Members: Craig Hogan; Stephan S. Meyer
KICP Students: Lee McCuller
New ultra-sensitive instrument aims to detect hints of elusive dark matter particles
The University of Chicago News Office, November 11, 2015
New ultra-sensitive instrument aims to detect hints of elusive dark matter particles
The University of Chicago News Office

There is five times more dark matter in the universe than "normal" matter - the atoms and molecules that make up the familiar world. Yet, it is still unknown what this dominant dark component actually is. On Nov. 11 an international collaboration of scientists inaugurated the new XENON1T instrument designed to search for dark matter with unprecedented sensitivity at the Gran Sasso Underground Laboratory in Italy.

Dark matter is one of the basic ingredients of the universe, and searches to detect it in laboratory-based experiments have been conducted for decades. However, until today dark matter has been observed only indirectly, via its gravitational interactions that govern the dynamics of the cosmos at all length-scales. It is expected that dark matter is made of a new, stable elementary particle that has escaped detection so far.

"We expect that several tens of thousands of dark matter particles per second are passing through the area of a thumbnail," said Luca Grandi, a UChicago assistant professor in physics and a member of the Kavli Institute for Cosmological Physics. "The fact that we did not detect them yet tells us that their probability to interact with the atoms of our detector is very small, and that we need more sensitive instruments to find the rare signature of this particle."

Grandi is a member of the XENON Collaboration, which consists of 21 research groups from the United States, Germany, Italy, Switzerland, Portugal, France, the Netherlands, Israel, Sweden and the United Arab Emirates. The collaboration's inauguration event took place Nov. 11 at the Laboratori Nazionali del Gran Sasso, one of the largest underground laboratories in the world.

"We need to put our experiment deep underground, using about 1,400 meters of solid rock to shield it from cosmic rays," said Grandi, who participated in the inauguration along with guests from funding agencies as well as journalists and colleagues. About 80 visitors joined the ceremony at the laboratory's experimental site, which measures 110 meters long, 15 meters wide and 15 meters high.

There, the new instrument is installed inside a 10-meter-diameter water shield to protect it from radioactive background radiation that originates from the environment. During introductory presentations, Elena Aprile, Columbia University professor and founder of the XENON project, illustrated the evolution of the program. It began with a 3 kilogram detector 15 years ago. The present-day instrument has a total mass of 3,500 kilograms.

Fighting against radioactivity
XENON1T employs the ultra-pure noble gas xenon as dark matter detection material, cooled down to -95 degrees Celsius to make it liquid.

"In order to see the rare interactions of a dark matter particle in your detector, you need to build an instrument with a large mass and an extremely low radioactive background," said Grandi.

"Otherwise you will have no chance to find the right events within the background signals."

For this reason, the XENON scientists have carefully selected all materials used in the construction of the detector, ensuring that their intrinsic contamination with radioactive isotopes meet the low-background experiment’s requirement.

"One has to realize that objects without any radioactivity do not exist," Grandi explained. "Minute traces of impurities are present in everything, from simple things like metal slabs to the walls of the laboratory to the human body. We are trying to reduce and control these radioactive contaminants as much as possible."

The XENON scientists measure tiny flashes of light and charge to reconstruct the position of the particle interaction within their detector, as well as the deposited energy and whether it might be induced by a dark matter particle or not. The light is observed by 248 sensitive photosensors, capable of detecting even single photons. A vacuum-insulated double-wall cryostat, resembling a gigantic version of a thermos flask, contains the cryogenic xenon and the dark matter detector.

The xenon gas is cooled and purified from impurities in the three-story XENON building, an installation with a transparent glass facade next to the water shield, which allows visitors to view the scientists inside. A gigantic stainless-steel sphere equipped with pipes and valves is installed on the ground floor.

"It can accommodate 7.6 tons of xenon in liquid and gaseous form," said Aprile. "This is more than two times the capacity we need for XENON1T, as we want to be prepared to swiftly increase the sensitivity of the experiment with a larger mass detector in the near future."

Aiming for a dark matter detection
Once fully operational, XENON1T will be the most sensitive dark matter experiment in the world. Grandi's group has been deeply involved in the preparation and assembly of the xenon Time Projection Chamber, the core of the detector. His group is also in charge for the development of the U.S. computing center for XENON1T data analysis via the UChicago Research Computing Center, directed by Birali Runesha, in close cooperation with Robert Gardner and his team at the Computation Institute.

In addition to Columbia's Aprile, leading the other six U.S. institutions are Ethan Brown, Rensselaer Polytechnic Institute; Petr Chaguine, Rice University; Rafael Lang, Purdue University; Kaixuan Ni, University of California, San Diego; and Hanguo Wang, University of California, Los Angeles.

XEON1T's first results are expected in early 2016. The collaboration expects the instrument to achieve most of its objectives within two years of data collection. The researchers then will move their project into a new phase.

"Of course we want to detect the dark matter particle," Grandi said, "but even if we have only found some hints after two years, we are in an excellent position to move on as we are already now preparing the next step of the project, which will be the far more sensitive XENONnT."


Related Links:
KICP Members: Luca Grandi
Scientific projects: XENON1T
Eckhardt Research Center to begin new phase of ambitious science
The University of Chicago News Office, October 29, 2015
Image by Tom Rossiter Photography
Image by Tom Rossiter Photography
The University of Chicago News Office

The appetite for discovery at the new William Eckhardt Research Center was articulated by the University of Chicago’s very first Nobel laureate, astrophysicist Albert A. Michelson. "If a poet could at the same time be a physicist, he might convey to others the pleasure, the satisfaction, almost the reverence, which the subject inspires," Michelson wrote in his 1903 book Light Waves and Their Uses.

The Eckhardt Research Center enables precision science of many kinds, encompassing engineering in the quantum realm as well as studies of distant planets and cosmic evolution. In this sense too it carries on the spirit of Michelson, whose studies of light influenced microscopy as well as astronomy.

On Oct. 29 the UChicago community is celebrating the dedication of the Eckhardt Research Center, named for Chicago futures trader and alumnus William Eckhardt, SM'70, in recognition of his generous philanthropy to the sciences at the University of Chicago. The center is home to the Institute for Molecular Engineering and several sections of the Physical Sciences Division, including the Department of Astronomy and Astrophysics and the Kavli Institute for Cosmological Physics.

"We are excited that the William Eckhardt Research Center provides a sophisticated and beautiful home to support our distinctive programs in molecular engineering and astrophysics," said Provost Eric Isaacs. "IME has been successful in building a new model for molecular-level research with broad impact, and this facility will allow for even more ambitious work. Equally significant, this building befits the Department of Astronomy and Astrophysics long tradition of scientific eminence, and its continuing importance in that field of study."

The construction project was a collaboration of HOK, an architecture firm that specializes in the design of science and technology buildings, and Jamie Carpenter, an artist, sculptor, and architect known for his innovative work with light and glass.

The structure will be equipped with high-performance laboratories that will allow researchers to translate quantum information science into new technologies, develop instruments that can detect planets orbiting distant stars, and much more.

"We will find Earth-like planets and maybe signs of life from these planets," says Angela Olinto, the Homer J. Livingston Professor and chair of Astronomy and Astrophysics. "We will explore the most extreme events of the universe and try to explain what causes these events. We will study the first stars in the first galaxies ever assembled in the universe. We will also probe the most fundamental forces of the universe in the first tiny fraction of a second after the Big Bang."

Sharing the Eckhardt Center holds particular potential for new collaborations and interactions among scholars in the Institute for Molecular Engineering and the Physical Sciences.

"We will really span activities from the tiniest to the most gigantic," said Dean Matthew Tirrell, the founding Pritzker Director of IME and Argonne National Laboratory's deputy director for science. "Molecular engineering can contribute to astronomy and astrophysics via fabrication of new detectors and other instrumentation."

Fostering partnerships and interactions
One of the unique aspects of the Eckhardt Research Center is the Pritzker Nanofabrication Facility. Located in the first basement of the center, the innovative facility will allow for fabricating new features and devices at the nanoscale level, supporting IME's goal to solve societal issues with molecular-sized tools and solutions.

The nanofabrication lab "provides a unique research and development environment for the academic and industrial scientist interested in pursuing state-of-the-art micro- and nanoscale fabrication," says Andrew Cleland, the John A. MacLean Sr. Professor for Molecular Engineering Innovation and Enterprise, who will lead the facility. "We anticipate drawing researchers from the Chicago area, the Midwest, and nationally, both to use this facility and to establish collaborations with IME and UChicago researchers."

The breadth of scholarship at the Eckhardt Research Center is a good match for the Kavli Institute, which explores the profound connections between physics at the smallest and largest of scales - from quarks to the cosmos - with a focus on dark matter, dark energy, and how the universe began. The Kavli Institute will collaborate with IME researchers to create detectors for instruments that will make the most precise measurements of the cosmic microwave background - the microwave echo of the Big Bang.

"To recruit top faculty and top students requires the facilities to allow them to do the best science they can do," says Rocky Kolb, dean of the Physical Sciences Division and the Arthur Holly Compton Distinguished Service Professor of Astronomy and Astrophysics. "With the Eckhardt Research Center, we will have the facilities and the infrastructure that will allow our faculty and students to explore the cosmos - in ways they have never been able to before."

Exploring new fields and pushing boundaries
The center will create the first dedicated home for IME since it was created in 2011 in partnership with Argonne. Having all IME researchers in the same location, with diverse backgrounds ranging from chemical engineering to engineering physics to biomedical engineering, will be beneficial for future partnerships within IME itself, Tirrell said.

The idea of pushing research frontiers that cross disciplinary boundaries has permeated the Department of Astronomy and Astrophysics, the Kavli Institute, and the Institute of Molecular Engineering for years.

"We have, in astronomy, a reputation of being an innovative department that does new things," says Kolb. "We were the first department to do astrophysics. Particle cosmology really was developed here. It's part of our nature to explore new fields and transcend boundaries."

- Story includes material that first appeared on the Institute for Molecular Engineering website.


Related Links:
KICP Members: Edward W. Kolb; Angela V. Olinto; Michael S. Turner
A Japanese physicist and a Canadian physicist helped to show subatomic 'neutrinos' have mass
Inside Science, October 8, 2015
by Ben P. Stein, Inside Science

The 2015 Nobel Prize in physics has been awarded to a Japanese physicist and a Canadian physicist for discovering that abundant subatomic particles known as neutrinos can undergo changes in their identity, a process that requires the particles, once thought to be massless, to possess mass.

The prize goes jointly to Takaaki Kajita of the University of Tokyo in Japan and Arthur B. McDonald of Queen's University in Kingston, Canada "for the discovery of neutrino oscillations, which shows that neutrinos have mass." The two recipients were leaders of two major underground neutrino observatories on opposite sides of the world. Kajita was part of the Super-Kamiokande collaboration in Japan, and McDonald led a group at the Sudbury Neutrino Observatory, or SNO, in Canada.

"Neutrinos are a puzzle and this year's Nobel Prize in physics honors a fundamental step toward unveiling the nature of the neutrino," said Olga Botner, a member of the Nobel Committee for Physics and a professor of physics at Uppsala University in Sweden.

"This is a great prize," said physicist Michael Turner, director of the Kavli Institute for Cosmological Physics at the University of Chicago. He added that this is the latest of four neutrino-related Nobel Prizes, from 1988 to 2015.

Today's announcement was "doubly wonderful," said Gene Beier, a professor of physics at the University of Pennsylvania who was a U.S. co-spokesperson for the SNO experiment. Beier had also worked in the Kamiokande II experiment, a predecessor to Super-Kamiokande.

Both experiments provided big answers.

"Neutrinos are among the fundamental particles," explained McDonald by phone during this morning's Nobel announcement in Sweden.

"The neutrino has a mass and it's more than a million times lighter than the electron," said Botner.

"Neutrinos punch above their weight. They contribute as much mass as stars do," Turner said.

The prize goes jointly to Takaaki Kajita of the University of Tokyo in Japan and Arthur B. McDonald of Queen's University in Kingston, Canada "for the discovery of neutrino oscillations, which shows that neutrinos have mass." The two recipients were leaders of two major underground neutrino observatories on opposite sides of the world. Kajita was part of the Super-Kamiokande collaboration in Japan, and McDonald led a group at the Sudbury Neutrino Observatory, or SNO, in Canada.


Related Links:
KICP Members: Michael S. Turner
Turner on Physics Nobel: Research Showing Neutrinos Have Mass Awarded Nobel Prize
Here and Now, October 8, 2015
The portraits of the winners of the Nobel Prize in Physics 2015 Takaaki Kajita (L) and Arthur B McDonald are displayed on a screen during a press conference of the Nobel Committee to announce the winner of the 2015 Nobel Prize in Physics on October 6, 2015 at the Swedish Academy of Sciences in Stockholm, Sweden. Takaaki Kajita of Japan and Canada's Arthur B. McDonald won the Nobel Physics Prize for work on neutrinos. (Jonathan Nackstrand/AFP/Getty Images)
The portraits of the winners of the Nobel Prize in Physics 2015 Takaaki Kajita (L) and Arthur B McDonald are displayed on a screen during a press conference of the Nobel Committee to announce the winner of the 2015 Nobel Prize in Physics on October 6, 2015 at the Swedish Academy of Sciences in Stockholm, Sweden. Takaaki Kajita of Japan and Canada's Arthur B. McDonald won the Nobel Physics Prize for work on neutrinos. (Jonathan Nackstrand/AFP/Getty Images)
Here and Now

October 6, 2015 at the Swedish Academy of Sciences in Stockholm, Sweden. Takaaki Kajita of Japan and Canada's Arthur B. McDonald won the Nobel Physics Prize for work on neutrinos. (Jonathan Nackstrand/AFP/Getty Images)

Looks like John Updike's poem about neutrinos being mass-less objects, "Cosmic Gall," might need an update.

Takaaki Kajita of Japan and Arthur McDonald of Canada have been awarded the Nobel Prize in Physics for their discovery that the subatomic particles called neutrinos do have mass. Scientists have called this a historic and major discovery.

Michael Turner, director of the Kavli Institute for Cosmological Physics at the University of Chicago, tells Here & Now's Jeremy Hobson how this discovery has changed scientists' understanding of the universe.

"The universe has so many neutrinos that they contribute as much to the mass budget of the universe as do the stars we see in the sky," Turner said.

He says the neutrino, which he affectionately calls a "lightweight," may be able to tell us about the origins of matter.

"The atoms that you and I are made out of, we believe that neutrinos in the early universe had a role in creating the ordinary matter that we're made out of," Turner said.

Correction: After our interview aired, Professor Turner sent us this correction: "It is now four Nobels for the neutrino: 1988 for the discovery of the muon neutrino; 1995 for the discovery of the neutrino itself; 2002 for solar and supernova neutrinos; and 2015 for neutrino mass. What a particle!"

Guest: Michael Turner, director of the Kavli Institute for Cosmological Physics at the University of Chicago.


Related Links:
KICP Members: Michael S. Turner
Three New Kavlis and Brain Initiative: The Kavli Foundation and University Partners Commit $100 Million to Brain Research
The Kavli Foundation, October 7, 2015
Three New Kavlis and Brain Initiative: The Kavli Foundation and University Partners Commit $100 Million to Brain Research
The Kavli Foundation

WASHINGTON, D.C. - Thursday, October 1 - The Kavli Foundation and its university partners announced today the commitment of more than $100 million in new funds to enable research aimed at deepening our understanding of the brain and brain-related disorders, such as traumatic brain injuries (TBI), Alzheimer's disease and Parkinson's disease.

On October 1, 2015 a bipartisan briefing was held on Capitol Hill regarding a new commitment to support brain research and an update on the BRAIN Initiative. Including details about new funding and research endeavors and a discussion that will focus on the BRAIN Initiative and on the future of neuroscience. Joining the discussion will be leaders from the White House Office of Science and Technology Policy, the National Institutes of Health, and the National Science Foundation.

"We are delighted to announce this major commitment to promoting a sustained interdisciplinary effort to solve the mysteries of the brain," said Rockell N. Hankin, Chairman of the Board of Directors at The Kavli Foundation. "By transcending the traditional boundaries of research, the new neuroscience institutes will make breakthrough discoveries possible."

The majority of the funds will establish three new Kavli neuroscience institutes at the Johns Hopkins University (JHU), The Rockefeller University and the University of California, San Francisco (UCSF). These institutes will become part of an international network of seven Kavli Institutes carrying out fundamental research in neuroscience, and a broader network of 20 Kavli Institutes dedicated to astrophysics, nanoscience, neuroscience and theoretical physics.

The new funding will support research that moves forward the national Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative, a public and private collaboration launched by President Obama in April 2013. At the time of the President's announcement, The Kavli Foundation publicly pledged to spend $40 million in support of basic neuroscience research. "With this announcement, the Foundation more than meets this commitment," said Robert W. Conn, President and CEO of The Kavli Foundation. "The establishment of three new institutes, along with the added investment in our existing neuroscience institutes, will further empower great scientists to help write the next chapter in neuroscience."

The BRAIN Initiative is supported by federal agencies, including the National Institutes of Health, National Science Foundation, and the Defense Advanced Research Projects Agency, and private partners such as The Kavli Foundation.

"The President launched the BRAIN Initiative to help unlock the mysteries of the brain, to improve our treatment of conditions like Alzheimer's and autism, and to deepen our understanding of how we think, learn, and remember. The Kavli Foundation is responding to the President's call to action by making investments to advance the goals of the BRAIN Initiative. I hope this spurs other private, philanthropic, and academic institutions to support this important initiative," said John P. Holdren, PhD, assistant to the President for Science and Technology, and director of the White House Office of Science and Technology Policy.

The three new institutes are the Kavli Neuroscience Discovery Institute at JHU, the Kavli Neural Systems Institute at The Rockefeller University and the Kavli Institute for Fundamental Neuroscience at UCSF. Each of the Institutes will receive a $20 million endowment supported equally by their universities and the Foundation, along with start-up funding. The Foundation is also partnering with four other universities to build their Kavli Institute endowments further. These Institutes are at Columbia University, the University of California, San Diego, Yale University and the Norwegian University of Science and Technology.

The BRAIN Initiative calls specifically for establishing new interdisciplinary collaborations aimed at creating novel new technologies for visualizing the brain at work.

"The cultivation of diverse partnerships, with government, big and small business, non-profits and academia, is a critical step on the path to unravel the mysteries of the brain," National Science Foundation Director France Cordova, PhD, said. "Only through continued investments in collaborative, fundamental research will we develop the innovative tools and technologies needed to help us understand the brain, which is the ultimate goal of the BRAIN Initiative. Progress in this area will bolster America's health, economy and security."

In the spirit of the interdisciplinary charge of the BRAIN Initiative, the new Kavli Institutes each work across their universities and with outside partners:
- The mission of the new Kavli Neuroscience Discovery Institute (Kavli NDI) at JHU is to bring together neuroscientists, engineers and data scientists to investigate neural development, neuronal plasticity, perception and cognition. "The challenges of tomorrow will not be confined to distinct disciplines, and neither will be the solutions we create," said Johns Hopkins University President Ronald J. Daniels. "The Kavli Foundation award is a tremendous honor, because it allows Johns Hopkins to build on our history of pioneering neuroscience and catalyze new partnerships with engineers and data scienctists that will be essential to building a unified understanding of brain function."
- At The Rockefeller University, the Kavli Neural Systems Institute (Kavli NSI) will also promote interdisciplinary research and learning to tackle the biggest questions in neuroscience through high-risk, high-reward projects and the development of new research technologies. "Kavli's investment in neuroscience at Rockefeller will enable us to create and share new research approaches and laboratory technologies to capture the possibilities of neuroscience from the micro to the macro level," said Rockefeller President Marc Tessier-Lavigne, PhD. "For example, Rockefeller scientists are currently developing a number of tools to push neuroscience forward, including advanced neuronal recording capabilities, sophisticated three-dimensional imaging, and non-invasive activation of neural circuits, among others."
- The Kavli Institute for Fundamental Neuroscience (Kavli IFN) at UCSF will focus initially on understanding brain plasticity, the remarkable capacity of the brain to modify its structure and function. The Kavli IFN will partner with engineers at two San Francisco Bay-area national laboratories to develop new tools and approaches to brain research. "UCSF scientists have made some of the seminal discoveries in modern neuroscience," said UCSF Chancellor Sam Hawgood, MBBS. "The Kavli Institute will sustain this rich tradition into the 21st Century."

"While private funding should never supplant federal funding," said Conn, "the scientific enterprise also depends on philanthropic giving to catalyze pioneering new directions and discoveries."

"Understanding the complex language of brain circuits - and how they function in both health and disease - is one of the greatest challenges in science. This effort will be made possible by cooperation across disciplines to build the advanced tools necessary to probe the brain in fine detail. The commitment of both public and private organizations brings much needed firepower and interdisciplinary expertise to this endeavor," said Walter Koroshetz, MD, director of the National Institute of Neurological Disorders and Stroke and the co-chair of the NIH BRAIN Initiative.

Cosmic convergence
AAAS, Science, August 3, 2015
This lab at the South Pole gathers signals from the massive IceCube detector 1.5 kilometers below.  <i>PHOTO: FELIPE PEDREROS, ICECUBE/NSF</i>
This lab at the South Pole gathers signals from the massive IceCube detector 1.5 kilometers below.

by Adrian Cho, AAAS, Science

A year and half ago, physicists working with one of the world's odder scientific instruments scored a bittersweet breakthrough. The massive IceCube particle detector - a 3D array of 5160 light sensors buried kilometers deep in ice at the South Pole - spotted ghostly subatomic particles called neutrinos from beyond our galaxy (Science, 22 November 2013, p. 920). Researchers had previously detected lower energy neutrinos gushing from the sun and raining down from particle interactions in the atmosphere. But - except for a burp from a nearby supernova explosion in 1987 - neutrinos from the far reaches of the cosmos had eluded capture.

The discovery is Nobel-caliber stuff, some physicists say, but it also sounded a cautionary note. IceCube saw only about a dozen cosmic neutrinos per year. At that meager rate, the $279 million detector might never spot enough of them to work as advertised: as a neutrino telescope that could open up a whole new view of the heavens.

But as the data continue to come in, researchers are optimistic. After all, the fact that cosmic neutrinos have been spotted means that a big enough detector should be able to harvest enough of them to study the sky, says Francis Halzen, a theoretical physicist at the University of Wisconsin, Madison, and the driving force behind IceCube. "We see the flux, and now we have to figure out what it takes to do astronomy with it," he says. Halzen and his team are pushing to expand IceCube, which already fills a volume of a cubic kilometer. Meanwhile, other researchers have developed approaches that they say could be cheaper and more efficient.

More important, cosmic neutrinos are already telling a story, especially when combined with other particles from space: highly energetic photons called gamma rays, and ultrahigh-energy cosmic rays - protons and heavier atomic nuclei that reach energies a million times higher than humans have achieved with particle accelerators. Physicists have long wondered where in the universe the most energetic neutrinos, gamma rays, and cosmic rays are born. Now, in a tantalizing convergence, all three questions appear to share the same answer, says Olga Botner, a physicist and IceCube team member from Uppsala University in Sweden. "We believe that the engines that generate the cosmic rays also generate the gamma rays and neutrinos," she says.

If so, physicists have only one mystery to solve. The convergence also suggests the solution won't require exotic new particle physics: The conventional astrophysics of stars and galaxies should suffice.

AS TRACERS of the heavens, neutrinos offer many advantages over other particles from space. Electrically charged cosmic rays swirl in galactic magnetic fields; gamma rays tangle with radiation lingering from the big bang - the cosmic microwave background (CMB). Uncharged neutrinos, by contrast, zoom straight from their sources through almost everything the universe throws at them. "Neutrinos are the ultimate high-energy messenger," says Abigail Vieregg, a physicist at the University of Chicago in Illinois. "They're perfect - if you can see them."


Related Links:
KICP Members: Abigail G. Vieregg
The Fabric of the Universe
UChicago Arts, July 15, 2015
The Fabric of the Universe
UChicago Arts

Benedikt Diemer (Ph.D candidate, Astronomy & Astrophysics, UChicago); Isaac Facio (MFA candidate, Fiber & Material Studies, SAIC)

Faculty Advisors: Andrey Kravtsov (Astronomy & Astrophysics, UChicago); Helen Maria Nugent (Designed Objects (AIADO), SAIC)

The Fabric of the Universe is an investigation into a novel way of visualizing the structure of the universe: using 3-dimensional textiles. Isaac Facio and Benedikt Diemer will transform the shapes formed by the dark matter in large computer simulations into fabric using digital textile manufacturing technologies. The properties of the fabric, such as its opacity, will represent the properties of dark matter structures, such as their density. Ultimately, the textile will take shape in a large-scale sculpture of the dark matter filaments and nodes in the universe, known as the "cosmic web".

Funded by the Graduate Division, School of the Art Institute of Chicago (SAIC).


Related Links:
KICP Members: Andrey V. Kravtsov
KICP Students: Benedikt Diemer
Kavli Roundtable Discussion: "Dwarf Galaxies Loom Large in the Quest for Dark Matter"
The Kavli Foundation, June 24, 2015
Side-by-side images from the Dark Energy Survey indicate the difficulty of identifying a dwarf galaxy. The right image shows approximately 300 stars thought to belong to a newly discovered dwarf satellite galaxy of the Milky Way. These stars are farther away than foreground stars within the Milky Way, but much closer than background galaxies, both of which appear in the left image but are blacked out in the right image. (Credit: Fermilab/Dark Energy Survey)
Side-by-side images from the Dark Energy Survey indicate the difficulty of identifying a dwarf galaxy. The right image shows approximately 300 stars thought to belong to a newly discovered dwarf satellite galaxy of the Milky Way. These stars are farther away than foreground stars within the Milky Way, but much closer than background galaxies, both of which appear in the left image but are blacked out in the right image. (Credit: Fermilab/Dark Energy Survey)
by Adam Hadhazy, The Kavli Foundation

A batch of newly discovered satellite dwarf galaxies orbiting the Milky Way should help scientists better grasp the evolution of the universe while also honing in on dark matter's identity.

IN ITS INAUGURAL YEAR OF OBSERVATIONS, the Dark Energy Survey has already turned up at least eight objects that look to be new satellite dwarf galaxies of the Milky Way. These miniature galaxies - the first discovered in a decade - shine with a mere billionth of our galaxy's brightness and each contains a million times less mass. Astronomers believe the vast majority of material in dwarf galaxies is dark matter, a mysterious substance composing about 80 percent of all matter in the universe. Dwarf galaxies have therefore emerged as prime targets for gathering potential clues about dark matter's composition.

Some theories suggest dark matter particles and antiparticles should produce telltale gamma rays when they collide with each other. Accordingly, scientists used the Fermi Gamma-Ray Space Telescope to study the newfound dwarf galaxy candidates, as well as a group of dwarf galaxies already on the books.

The telescope detected no significant gamma-ray signals from either set of dwarf galaxies, however, leaving scientists still in the hunt for dark matter. Four studies earlier this spring from the Dark Energy Survey and Fermi announced this flurry of results.

On May 18, 2015, The Kavli Foundation spoke with three astrophysicists about the continuing search for dark matter data in space and how dwarf galaxies can help us understand the evolution of our universe.

The participants were:

  • JOSH FRIEMAN is the Director of the Dark Energy Survey at the Department of Energy's Fermilab Center for Particle Astrophysics, a Professor of Astronomy and Astrophysics at the University of Chicago, and a member of the Kavli Institute for Cosmological Physics (KICP).
  • ALEX DRLICA-WAGNER - is the Schramm Experimental Fellow at the Fermilab Center for Particle Astrophysics and a KICP Associate fellow.
  • ANDREA ALBERT - is a Research Associate at the SLAC National Accelerator Laboratory and the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) at Stanford University.

The following is an edited transcript of their roundtable discussion. The participants have been provided the opportunity to amend or edit their remarks.

THE KAVLI FOUNDATION: What were your first thoughts when you saw the signs of these dwarf galaxies in Dark Energy Survey data?

ALEX DRLICA-WAGNER: It was very exciting and definitely not something you get to experience every day. It was obvious from the start that some of the objects in the data were real stellar systems and very probable that they were new dwarf galaxies.

JOSH FRIEMAN: We released the first year of Dark Energy Survey data internally to our international collaboration of scientists in late December. Within a week or two, Alex and his co-lead author, Keith Bechtol, who is a postdoctoral research fellow at the Kavli Institute for Cosmological Physics, helped to lead the group of Dark Energy Survey scientists who identified these objects. Alex and Keith had spent a long time developing methods for detecting dwarf galaxies in this data, so when it became available they were instantly able to jump on it.

DRLICA-WAGNER: When you see something like this emerge from your data analysis for the first time, that's very special. You've invested so much time going through all of the data, you can feel a little lost down there in all the details.

ANDREA ALBERT: Yeah, I know how that feels!

TKF: How did the Dark Energy Survey enable the discovery of these dwarf galaxies?

FRIEMAN: We didn't actually build the Dark Energy Survey to do this. These nearby dwarf galaxies are foreground objects to what we're really trying to study, which are hundreds of millions of distant galaxies. We are measuring those distant galaxies' properties and their distribution to figure out why the expansion of the universe is speeding up due to dark energy. We realized that those same data would be very useful not only for studying the distant universe, but also for identifying very faint dwarf satellite galaxies of our own Milky Way.

DRLICA-WAGNER: With the Dark Energy Camera, the principal instrument for the Dark Energy Survey, this is the first time we've had a super-sensitive, large-field digital camera in the southern hemisphere. The explosion of dwarf discoveries about a decade ago in the northern hemisphere was made possible because of the state-of-the-art technology involved in the Sloan Digital Sky Survey [SDSS]. With the Dark Energy Camera, we have an even better camera than SDSS and we have a whole new region of sky.

FRIEMAN: This is one of those examples where you build something with one goal in mind, but if it's properly designed it turns out to be quite useful for a variety of other scientific studies as well.

DRLICA-WAGNER: As Josh just said, the Dark Energy Survey was not intended for this kind of science, but it really presented an amazing opportunity. We were able to find this abundance of new stellar systems by combining two models of what we expect dwarf galaxies to look like. In general, dwarf galaxies have more stars near their centers and fewer stars near their peripheries. Additionally, the stars in dwarf galaxies tend to follow a very distinct pattern of color and brightness. By combining these two models, we had a much better chance of finding dwarf galaxies.

TKF: Why are dwarf galaxies so notoriously difficult to spot?

DRLICA-WAGNER: Dwarf galaxies are hard to find because they contain very few bright stars. Also, dwarf galaxies are mostly made of dark matter. If we figured out a way to see dark matter, then dwarf galaxies would be easy to see.

ALBERT: We're awesome at seeing stars because we are awesome at seeing light. Unfortunately, dark matter does not directly make light. So we call it "dark." Physicists are not that creative when we come up with names!

FRIEMAN: One thing astronomers like to do when they're presenting at conferences is to show an image of what a dwarf galaxy looks like. The presenter will show an image and it looks like nothing is there, like a random field of stars. And then on the next slide, the astronomer will circle all the objects that are members of that dwarf galaxy, and then it pops out at you.

What you really need to find these dwarf galaxies are very sensitive observations that allow you to detect faint stars and determine their colors. All that is critical for being able to distinguish a grouping of stars that together form a dwarf galaxy from the light of background galaxies and from foreground stars in the Milky Way.

ALBERT: I'd also mention that many of the reasons why dwarf galaxies are very, very challenging to detect are also the reasons why they are one of the best targets we have today for dark matter searches.

TKF: That comment segues into why dwarf satellite galaxies of the Milky Way are so scientifically valuable. Alex, you've said before that their dark matter content makes them important for both astronomy and physics. Can you elaborate?

DRLICA-WAGNER: This long-standing problem of the identity of dark matter is a topic where you historically have seen a lot of interplay between astronomy and physics. Dark matter was first a purely astronomical problem. It was originally discovered by observations showing that the force of gravity is not strong enough to prevent galaxies and clusters of galaxies from flying apart. So astronomy at the very start was sort of telling physics, "Hey, there's something here that we don't understand." In parallel physicists, were coming up with their own ideas for new fundamental particles. Eventually, people started to assemble the idea that missing "dark" matter particles could be holding galaxies together.

FRIEMAN: This notion of dark matter particles goes back 35 years or so and it's very compelling. Assume you have an unseen particle that weighs, say, 10 to 100 times the mass of a proton. Say it only rarely interacts with particles of normal matter through a force similar to the "weak force," one of the four known forces of nature. Particles with these properties would very naturally be around in the right amounts in the universe to be the dark matter that we infer in galaxies and clusters of galaxies. The particles would also possess the right properties to explain the formation of galaxies and larger structures.

DRLICA-WAGNER: This melding of ideas from astronomy and physics has really come together to make a cosmic frontier of physics. We're trying to push our fundamental understanding of physics through a better understanding of the cosmos with observations like those from the Dark Energy Survey.

TKF: Dwarf galaxies and the search for dark matter particles are a prime example of the intersection of astronomy and physics. Andrea, your specialty is looking for the signatures of dark matter particles that hypothetically self-annihilate, rather like how normal matter particles and antimatter particles annihilate each other. This annihilation should generate telltale gamma rays. Yet the Fermi Gamma-Ray Space Telescope hasn't glimpsed gamma-ray signatures from dwarf galaxies, including the newly discovered dwarfs, that are suggestive of dark matter. What is your reaction to this?

ALBERT: It is disappointing. I think anyone who says that it's exciting that we haven't discovered particles of dark matter is a liar. [Laughter] So yes, we have not seen dark matter yet. However, we are just starting to scratch the surface. We have calculated a rate at which we expect annihilations to occur, according to various models, and determined what the gamma-ray signature of these annihilations should be. This annihilation rate and its gamma-ray signals are tied to the mass of the dark matter particles. At this point, we have just started to test for the most promising dark matter candidates across a small range of masses. There are models for more massive dark matter particles than we can now detect with Fermi, and which are just as viable. So I think that if dark matter is hiding, we are narrowing in on it, and that's exciting.

FRIEMAN: There's a real synergy between the Dark Energy Survey, which is an optical survey of the sky, and the Fermi experiment, which is searching over the whole sky for gamma rays. It has been very exciting putting these two projects together to make progress in constraining dark matter. I agree with Andrea that even though the latest studies report a non-detection of signature gamma rays, it's nevertheless important progress in constraining what the dark matter could be. And I think it's pushing us closer to either detecting dark matter particles or having to go in a different direction to explain dark matter.

ALBERT: The search for dark matter reminds me of the history of the search for the Higgs boson, which we finally discovered in 2012 at the Large Hadron Collider [LHC] at CERN. A couple of years before then, we were looking for the Higgs boson in the less powerful Tevatron particle accelerator at Fermilab. An experiment there was one of the first to rule out certain masses of the Higgs boson. That told us we needed to go and build a better accelerator before we would actually find the thing. Fermi's been running for over six years now, but there is a new gamma-ray experiment in the making called the Cherenkov Telescope Array. It is going to be able to test for much heavier dark matter particle masses inaccessible to Fermi.
"Many of the reasons why dwarf galaxies are very, very challenging to detect are also the reasons why they are one of the best targets we have today for dark matter searches." - Andrea Albert

TKF: How else can dwarf galaxies help us pin down the properties of dark matter?

DRLICA-WAGNER: It's worth noting that there are multiple targets in the sky where you'd expect to see a gamma-ray signal from dark matter. One of the most tantalizing is the center of the Milky Way galaxy itself. Unfortunately, the center of our Galaxy is a very active region, and there are loads of gamma rays coming from there. The issue is that when you see these gamma rays, it could just be that you don't fully understand how our Galaxy's center is producing them astrophysically. Or, on the other hand, there could be a dark matter component to the gamma-ray emissions. Dwarf galaxies are extremely important because you can use them as a cross-check on any interesting signals you see from the Galactic center.

ALBERT: Interpreting this excess of gamma rays from the Milky Way's center as possibly coming from dark matter annihilations highlights how important it is to have a large sample of these dwarf galaxies. The Galactic center is close to us and it's really bright in gamma rays, whereas these dwarf galaxies are like little, dim candles. So how are we ever going to compare dwarf galaxies to the big, bright Galactic center? If we have enough dwarf galaxies, we can stack up them up statistically for a comparison, so we can then start to test and rule out models that don't fit the data.

DRLICA-WAGNER: That's right. While we will likely have a smaller gamma-ray signal from dwarf galaxies, the signal is much cleaner and easier to study than from the very active center of the Milky Way galaxy.
"We're trying to push our fundamental understanding of physics through a better understanding of the cosmos with observations like those from the Dark Energy Survey." - Alex Drlica-Wagner

TKF: By finding these new satellite dwarf galaxies of the Milky Way, do you think we're closer to solving the so-called missing satellite problem? According to the leading theory of Big Bang cosmology, known as the cold dark matter model, there should be hundreds of satellite dwarf galaxies orbiting the Milky Way. Yet we've only found a few dozen. Are we now starting to plug this gap?

FRIEMAN: This has been an interesting problem and it gets into the cosmological issue of the formation of structure in the universe, of how galaxies and galaxy clusters came to be. One of the exciting things about dwarf galaxies is that they are likely some of the first large structures that formed in the universe. In the cold dark matter model, structure forms hierarchically. That means that smaller structures formed first and then merged together to form larger structures, made of both dark matter and galaxies.

DRLICA-WAGNER: The population of dwarf galaxies tells us something about how galaxies form. They address larger astrophysical questions about how our galaxy came to be and how other large galaxies form from gathering up the small, original galaxies in the universe.

FRIEMAN: There is this issue, though, when you run a computer simulation of how structure forms in the cold dark matter model. A galaxy with a similar size as the Milky Way ends up with a halo of dark matter surrounding it. But this halo should have lots of clumps within it that have masses comparable to those of dwarf galaxies. The assumption is that since dark matter and normal matter clump together due to gravity, you would naively expect those dark matter clumps to be where dwarf galaxies form. In other words, the dark matter halo around our galaxy should be teeming with hundreds of dwarf galaxies or more, but we see only a few. The missing satellite problem is that there's a mismatch between the number of dwarf galaxies found and the number predicted from theory.

As we've drilled down deeper, further and fainter with the SDSS and now with the Dark Energy Survey, we are finding more dwarf galaxies. But that's only one piece of the puzzle. You also have to understand the detailed physics of galaxy formation to say whether those clumps of dark and normal matter in the Milky Way halo would actually have formed stars that we can see. There are some scenarios in which you don't expect all of those clumps to have lit up and formed dwarf galaxies. So I would say this finding of the eight new dwarf galaxies helps inform the missing satellite problem, but it also wasn't the problem that was keeping theorists up at night the last few years.

ALBERT: An astrophysical problem that I'm hearing people talk more about these days is the "too big to fail" problem. The problem is, why don't we see larger dwarf galaxies? Why isn't matter clumping on a larger scale than the dwarf galaxies, but on a smaller scale than the Milky Way galaxy?

FRIEMAN: To date, we've had roughly 25 dwarf galaxies to study with regard to the sizes they attain in the dark matter around the Milky Way. In the next few years, as we get more information on the new dwarf galaxies we've found, plus other new ones, that number will increase. That should help us quantify the "too big to fail" problem and decide how much of a problem it is.

TKF: Do you think the Dark Energy Survey will turn up more dwarf galaxies?

FRIEMAN: We found these dwarf galaxies in the Dark Energy Survey's first six-month season of observations. We'll have five of these observing seasons over five years. During the first season, we observed about 40 percent of the area of the sky we will eventually cover. In the second season, which ended in February, we observed most of the remainder of the sky area, so we are hoping for a good harvest of new dwarfs. In the subsequent seasons, we won't cover new areas, but we will take deeper observations of the previously covered area. In principle, that can enable us to find dwarf galaxies we haven't spotted yet that have fainter or fewer stars in them.

DRLICA-WAGNER: Over these later seasons, we will also gain a better understanding of the dwarf galaxies we have already found. As for the number of new dwarfs we'll find, we'd expect to find maybe 10 more based on the area of the survey we have covered and the additional area we are adding. But there are important caveats, such as whether dwarf galaxies are distributed evenly across the sky. It's an open scientific question that we hope to address with future years of the Dark Energy Survey.
"These new dwarf galaxies are perhaps some of the earliest structures that formed in the universe and are the building blocks of the large-scale structure we see today." - Josh Frieman

TKF: Josh, you've said that cosmology is like archeology on a grand scale. Just as an archaeologist might look at ruins or pottery shards to piece together an ancient society, we can see how galaxies are distributed in space to learn what the universe looked like in the past. Can these new dwarf galaxies help us trace back the history of the Milky Way and the universe?

FRIEMAN: You can think of these dwarf galaxies as pottery shards left over from an earlier period of cosmic evolution. These new dwarf galaxies are perhaps some of the earliest structures that formed in the universe and are the building blocks of the large-scale structure we see today. They're much smaller than the mass of the Milky Way, and some of these dwarfs appear to have stars in them that are quite old. So these dwarf galaxies are potentially an indicator of what happened in the early phases of structure formation.

The first two major results from the Dark Energy Survey are kind of poetic when viewed in juxtaposition. One major result is these dwarf galaxies. The other is a large-scale dark matter map we released in April, which shows superclusters of galaxies and dark matter - some of the largest structures in the universe that have ever been seen. So surveys like the Dark Energy Survey are giving us information over this very broad range of scales, from dwarf galaxies to superclusters, that add to our picture about how structure has formed and evolved over time. And that's important also for the main thing that we want to do with the Dark Energy Survey, which is understand why the expansion of the universe is speeding up due to dark energy. There's a grand competition taking place on the largest scales of the universe between gravity trying to pull things together and dark energy trying to push things apart. Understanding how structure formed and evolved over time is one of the tools that we will use to figure out the nature of dark energy.

TKF: Alex and Andrea, do you guys also feel like cosmic archeologists? Or maybe more like cosmic bounty hunters trying to capture dwarf galaxies and their signals of dark matter annihilation?

ALBERT: I feel like a cosmic Sherlock Holmes. All of the dark matter analyses I've been involved in have not seen anything, so it feels like dark matter is just out of my grasp. Dark matter is kind of like my Moriarty.

DRLICA-WAGNER: My thesis was similar to Andrea's work searching for dark matter annihilation in gamma rays. One thing that I've learned from the recent discoveries in DES is that it is really, really fun to find things. I can only imagine how extraordinarily exciting it will be if and when we find definitive evidence of dark matter.

ALBERT: It would be a bigger finding than the Higgs boson. It would be evidence for physics beyond the Standard Model of particle physics that is a great description of the 20 percent of normal matter in the universe which actually only makes up five percent of the grand total of the total mass and energy in the universe.

FRIEMAN: Yes, we can say we have a really, really good understanding of five percent of the universe.

ALBERT: There's a quote that resonates with me and my feelings toward finding dark matter that people attribute to Confucius: "The hardest thing of all to find is a black cat in a dark room, especially if there is no cat." Fortunately, at this point, I don't think we've searched the entire room!

- Adam Hadhazy, Summer 2015


Related Links:
KICP Members: Alex Drlica-Wagner; Joshua A. Frieman
Scientific projects: Dark Energy Survey (DES); Sloan Digital Sky Survey (SDSS)
Chicago blues and the science in sound
The University of Chicago News Office, June 19, 2015
Bradford Benson, KICP senior member
Bradford Benson, KICP senior member
by Greg Borzo, The University of Chicago News Office

'Science and Sound' Preview Video

Everyone knows about visualizing data, but few have heard of sonifying data. Nevertheless, sound has great potential for organizing, interpreting and sharing scientific knowledge. Sound can also be a powerful tool to learn more about culture and the natural world.

Citing microbial bebop, Chicago blues, cosmic sound and a string quartet inspired by DNA's double helix, panelists at a program called "Science and Sound" on June 3 made a strong case for exploring and exploiting sound as a tool in scientific endeavors.

The occasion was the 11th in a series of joint speaker events for faculty at the University of Chicago as well as scientists, researchers and engineers at Argonne National Laboratory and Fermi National Accelerator Laboratory. It was held at Buddy Guy's Legends, the "cathedral" of Chicago blues and the "perfect place to discuss how sound serves science, pervades our lives and influences our emotions," said Donald Levy, vice president for Research and for National Laboratories at the University of Chicago.

Panelist Peter Larsen, assistant computational biologist at Argonne, explained how an algorithm he calls microbial bebop generates data into music by normalizing the data to a dynamic range of integer values and mapping those values to notes and chords. "I doubt that I'll ever come up with a composition that will change my understanding of microbial ecology, but the very exercise of doing this has already accomplished that," he said. "My job is to think of interesting ways to analyze big data... and microbial bebop has helped me find and understand better approaches to understanding data."

Another panelist, however, decided not to transcribe data directly into music, realizing that such an approach would not create an effective, cohesive composition. In composing "Helix Spirals" for string quartet, Grammy-winning composer Augusta Read Thomas, University Professor of Composition, approached the project metaphorically. She found inspiration in science and showed how well music can present an abstract and intellectual expression of nature.

"Helix Spirals" celebrates the Meselson-Stahl DNA replication experiment of 1958. The first movement, Thomas explained, portrays loci, that is, specific but "flickering" locations of genes or DNA sequences on a chromosome. The second movement portrays DNA replication with different instruments representing different strands. And the third conveys the beauty, richness and force of life.

"Nature is a great teacher of transformation, connections and, for me, music composition," said Thomas, who is now working on a piece about protein folding.

Indeed, music and sound is a "metaphor for the regularity of nature and even the movement of the heavens," said moderator Sidney Nagel, the Stein-Freiler Distinguished Service Professor in Physics.

Listening to learn
Instead of using science to generate or inspire music, panelist Michael Dietler, professor in anthropology, works the other way around. He listens to music to better understand cultures. "Music is a socially patterned, cultural phenomenon, and the blues has a lot to teach us about Chicago's African American culture," he said. Noting that many students spend four years on campus without exploring what Chicago has to offer, Dietler created a course on the history of the blues, which he called an enormously influential form of music.

"It's one thing to listen to the blues and quite another to understand how it evolved, impacts people, influences culture and continues to develop today," Dietler said. The difference is akin, he added, to the difference between enjoying the sound of French and actually understanding what is being said, idiomatically, historically and culturally.

Meanwhile, one of the best ways to learn about the universe is to listen to it. "Just like you can learn a lot about an instrument by studying the frequency of the sound it makes, you can learn a lot about the content of the universe by studying the Cosmic Microwave Background," said Bradford Benson, associate scientist and Wilson fellow at Fermilab and assistant professor in astronomy and astrophysics at the University of Chicago.

Cosmic Microwave Background is radiation left over from the Big Bang. "As we map the sky, we can detect sound waves from the early history of the universe, more than 13 billion years ago," Benson said. "When we measure the Cosmic Microwave Background's power spectrum - analogous to what you might do with a stereo amplifier - we find a remarkable harmonic structure," Benson said.

Overall, the panelists agreed that sound and science go well together, whether it is to listen to the cosmos - and each other - or to utilize sound as a tool to understand data and present knowledge, directly or indirectly. For instance, although microbial bebop is not an effective way to share data, it is a great way to engage students in science, Larsen has found. But the day may come when sonified data and audible pie charts are as commonplace as visual maps.

"We have to learn how to create and interpret charts, Venn diagrams, and other visual presentations of data," Dietler said. "Likewise, we could learn how to utilize sound and music more in science. We're used to conducting many things visually, but there's no reason why we couldn't handle more things audibly."

"Some of what we learn is communicated through sound, but there's a big potential to tap sound in new ways to achieve much more," Nagel concluded.


Related Links:
KICP Members: Bradford A. Benson
MIRA and marathons
Argonne, June 18, 2015
Katrin Heitmann, Salman Habib and Steve Rangel will be supporting HOPES and the Chicago Area Runners Association when they run The Chicago Marathon October 11.
Katrin Heitmann, Salman Habib and Steve Rangel will be supporting HOPES and the Chicago Area Runners Association when they run The Chicago Marathon October 11.
by Sarah Schlieder, Argonne

For three Argonne employees it's all about speed - both in and out of the lab.

Katrin Heitmann, a joint staff member in the High Energy Physics and Math and Computer Sciences Divisions; Salman Habib, senior physicist in the High Energy Physics and Math and Computer Sciences Divisions and Steve Rangel, lab appointee and Ph.D. student at Northwestern University have run the largest cosmological simulation on MIRA - one of the world's fastest supercomputers. Their aim was to create high-resolution simulations what would allow scientists to connect numerous surveys of the universe that measure the distribution of galaxies.

"Dealing with data is a big challenge in and of itself. What a large computer like MIRA enables is a lot of statistics." - Katrin Heitmann, Staff Member HEP and MCS

MIRA is capable of 10 quadrillion calculations per second. Located at the Argonne Leadership Computing Facility, it can do in one day what it would take the average personal computer 20 years to complete.

MIRA is also what brought Heitmann and Habib to Argonne from Los Alamos National Laboratory in Los Alamos, New Mexico.

Rangel joined the team soon after their move to Argonne. He said he first became interested in data science and data analysis when he was pursuing his master's degree. Later, his interest evolved into a passion for high performance computing.

"It was sort of a natural fit to come here and work with Salman and Katrin's group." - Steve Rangel, Ph.D. student at Northwestern University

The team has now begun to analyze the simulations, measuring galaxy distribution from a theory standpoint and comparing that data to observations of the universe. The team worked together to transform data from the MIRA simulation into an image that closely resembles the actual universe. Argonne joint staff member Nan Li and University of Chicago Professor Mike Gladders constructed the final visualization.

But besides performing the world's biggest simulation on MIRA, the team will put their own speed to the test later this year when they run the Bank of America Chicago Marathon.

The team ran together for the first time in this year's Bank of America Shamrock Shuffle, held March 29 in downtown Chicago. Rangel then suggested they run a marathon.

"At first I said, 'No way!'" Heitmann said. "Then, I got to thinking about it and thought it would be kind of cool if our group did it together. But I said we should at least do it for something more meaningful than just suffering for 26 miles."

With that idea in mind, Heitmann said she searched for charities listed on the Chicago Marathon website for which people can run. There, she found Chicago HOPES for Kids.

HOPES began in 2006 as an initiative of the Chicago Public Schools Department of Education Support for Students in Temporary Living Situations, or STLS. The organization collaborates with schools and shelters to establish after-school tutoring programs and provides students with additional support outside the classroom despite the challenges of homelessness, according to their website.

Heitmann and Habib will be running the marathon as part of the organization's team Hustle for Hopes. The money raised is used to purchase educational materials for the students.

"I like to support something local, that I can actually go see the students and meet with these people," Heitmann said.

Rangel will be running with the Chicago Area Runners Association (CARA) Road Scholars - a mentorship-based running program for at-risk Chicago area high school students. Mentors train students to successfully complete a half-marathon. The program also uses running to teach at-risk youth lessons in commitment, dedication and discipline, according to the CARA website. Funds raised by the marathon participants will be used to provide teens in the program with running shoes, transportation to training sites and cover race entry fees.

"I was lucky enough to start running when I was a kid," Rangel said. "For me, it really hits home."

The 26.2-mile marathon is scheduled to be held October 11 in downtown Chicago.


Related Links:
KICP Members: Michael D. Gladders; Salman Habib; Katrin Heitmann
John Carlstrom to receive Gruber Cosmology Prize for experimental explorations of universe
The University of Chicago News, June 11, 2015
Prof. John Carlstrom, Deputy Director of the PFC and the KICP
Prof. John Carlstrom, Deputy Director of the PFC and the KICP
The University of Chicago News

The 2015 Gruber Foundation Cosmology Prize has honored the University of Chicago's John E. Carlstrom, alumnus Jeremiah P. Ostriker, PhD'64, and Princeton University's Lyman Page for their individual and collective contributions to the study of the universe on the largest scales.

The 2015 prize is divided into two parts: half to a distinguished theorist, and the other half to two exceptional experimentalists. The theorist is Ostriker, a professor emeritus at Princeton University, now teaching at Columbia University. Ostriker, whose graduate school mentor was UChicago Nobel laureate Subrahmanyan Chandrasekhar, is being honored for his groundbreaking body of work over a five-decade career.

Carlstrom, the S. Chandrasekhar Distinguished Service Professor in Astronomy & Astrophysics, and Page, the Henry De Wolf Smyth Professor of Physics, have each overseen ground-based experiments that have provided a wealth of information about the origins and evolution of the universe. Carlstrom has worked extensively to study the cosmic microwave background, the relic radiation from the infancy of the universe, using the South Pole Telescope and other instruments.

"Together, the theoretical and experimental work of these three scientists has contributed to, clarified and advanced today's standard cosmological model," the Gruber Foundation wrote in announcing this year's prize.

Ostriker will receive half of the $500,000 award, while Carlstrom and Page will divide the other half. All three also will receive a gold medal Aug. 3 at the XXIX General Assembly of the International Astronomical Union in Honolulu, Hawaii.

Previous recipients of the Gruber Prize include Wendy Freedman, the University Professor in Astronomy & Astrophysics, who received the 2009 prize "for the definitive measurement of the rate of expansion of the universe, Hubble's Constant." One of the foremost awards in the field of cosmology, the prize honors "a leading cosmologist, astronomer, astrophysicist or scientific philosopher for theoretical, analytical, conceptual or observational discoveries leading to fundamental advances in our understanding of the universe," according to the Gruber Foundation.

Stephan Meyer, professor in astronomy & astrophysics, received a share of the prize in 2006 as a member of the Cosmic Background Explorer Team "for studies confirming that our universe was born in a hot Big Bang." He repeated the feat in 2012 as a member of the Wilkinson Microwave Anistropy Probe, which was honored for "exquisite measurements of anisotropies in the relic radiation from the Big Bang - the Cosmic Microwave Background."


Related Links:
KICP Members: John E. Carlstrom; Stephan S. Meyer
Scientific projects: South Pole Telescope (SPT)
2015 Gruber Prize in Cosmology: John E. Carlstrom
The Gruber Foundation, June 9, 2015
2015 Gruber Prize in Cosmology: John E. Carlstrom
The Gruber Foundation

The 2015 Gruber Prize in Cosmology honors theorist Jeremiah P. Ostriker for his lifetime of achievements and the experimentalists John E. Carlstrom and Lyman A. Page, Jr., for their pioneering observations of the cosmic microwave background (CMB), the relic radiation from the infancy of the universe's existence. Individually and collectively the works of these three scientists has helped to establish and advance the standard cosmological model: a universe that arose out of an inconceivably dense state of matter and energy, and has been expanding and cooling ever since, eventually coalescing into today's familiar skyscape of planets, stars, and galaxies.

During a five-decade career at Princeton University, Jeremiah Ostriker has made significant contributions to the studies of galaxy formation, the interstellar medium, and the intergalactic medium. He has also repeatedly challenged assumptions about how the universe works and proposed radical alternative interpretations. In 1972 he and Princeton colleague P. James E. Peebles created computer simulations that indicated either Newton's law of gravitation is wrong or some sort of invisible mass must be present to stabilize rotating spiral galaxies such as our own Milky Way. A year later, in collaboration with a postdoctoral fellow, Ostriker and Peebles surveyed existing data from a wide array of observations of individual galaxies and clusters of galaxies and concluded, in the opening sentence of a now-classic paper: "There are reasons, increasing in number and quality, to believe that the mass of ordinary galaxies may have been underestimated by a factor of 10 or more."

In 1995, Ostriker and another Princeton colleague, Paul J. Steinhardt, argued that the total amount of matter in the universe, dark or otherwise, is at odds with some key theoretical implications of the Big Bang interpretation of the universe. Ostriker and Steinhardt invoked yet another mysterious missing component that they said should be permeating the universe.

Today we call the missing components that Ostriker proposed in the 1970s and 1990s dark matter and dark energy, respectively -- abstract ideas that have been borne out by innumerable observations. In fact, while other theorists were making arguments similar to that of Ostriker and Steinhardt in the mid-1990s, what distinguishes their paper is the suggestion that this component should contribute about 70 percent to the total mass and energy of the universe --a figure validated by many later observations, including those made by the instruments overseen by Carlstrom and Page.

While both Page and Carlstrom have worked extensively in the study of the CMB, they lead two projects in particular. Carlstrom, who has been at the University of Chicago since 1995, is the principal investigator on the South Pole Telescope, which was constructed at the U. S. science station at the Pole in late 2006 and early 2007. Page, who has been at Princeton since 1990, serves in the same capacity for the Atacama Cosmology Telescope, which was constructed on Cerro Toco in the mountainous Atacama Desert in Chile in 2007.

Those instruments, both still active, probe the CMB, the relic radiation dating to the infancy of the cosmos. When the universe was 380,000 years old it had cooled enough for hydrogen atoms and photons to decouple and go their separate ways. That "flashbulb" moment has survived as a sort of snapshot -- a "baby picture" of the universe-- though over the past 13.7 billion years the expansion of space has stretched the light from the image all the way into the microwave end of the electromagnetic spectrum. Look closely enough and finely enough at the CMB, though, and you should be able to see extraordinarily subtle shadings in temperature: the DNA for the galaxies, clusters of galaxies, and super-clusters of galaxies that populate the universe as we know it.

Among the many contributions to cosmology that the South Pole Telescope and the Atacama Cosmology Telescope have made are: the discovery of hundreds of clusters of galaxies going back to when the universe was about one-third its present age, providing a history of the growth of the large-scale structure of the universe; independent verification that the universe consists of approximately 25 percent dark matter, 70 percent dark energy, and 5 percent atoms; and strong evidence that the structure in the CMB is a remnant of quantum fluctuations. This latter data is in excellent agreement with the model of inflation, a theoretical primordial hyper-expansion of space that would have determined the distribution of all that energy and matter.

What is dark matter? What is dark energy? How to explain a quantum universe? In honoring Carlstrom, Ostriker, and Page, the 2015 Gruber Cosmology Prize recognizes science doing what science does best: answering fundamental questions while opening new frontiers for observers and theorists alike and raising new fundamental questions to puzzle us.


Related Links:
KICP Members: John E. Carlstrom
Scientific projects: South Pole Telescope (SPT)
Prof. Daniel Holz receives Quantrell Award
The University of Chicago News Office, June 1, 2015
Daniel Holz, KICP senior member
Daniel Holz, KICP senior member
The University of Chicago News Office

The Llewellyn John and Harriet Manchester Quantrell Awards are believed to be the nation's oldest prize for undergraduate teaching. Presented annually, the awards reflect the College's commitment to honoring inspiring teachers. UChicago faculty often count the Quantrell among their most treasured honors.

"Ernest Quantrell, who first established the Quantrell Awards in 1937, wanted to honor faculty members who were great scholar-teachers and who inspired our students to become more enlightened thinkers and more effective citizens of their communities and of our nation," says John W. Boyer, dean of the College. "As teachers and as scholars and as citizens of the University at large, this year's Quantrell winners exemplify the very best about the College and the University."

Daniel Holz, Associate Professor, Physics
Soon after Daniel Holz learned of his Quantrell Award, he looked up the list of previous recipients.

"I was actually a graduate student here at UChicago, and I've had some of the previous recipients as professors. They're truly outstanding," says Holz, PhD'98, an associate professor in physics. "It's really an honor to be on the same list."


Related Links:
KICP Members: Daniel E. Holz
Honoring graduate teachers and mentors: Prof. Angela Olinto
The University of Chicago News Office, June 1, 2015
Angela V. Olinto, KICP senior member Homer J. Livingston Professor, Astronomy & Astrophysics
Angela V. Olinto, KICP senior member
Homer J. Livingston Professor, Astronomy & Astrophysics
The University of Chicago News Office

The 2015 Faculty Award for Excellence in Graduate Teaching and Mentoring

Angela V. Olinto
Homer J. Livingston Professor, Astronomy & Astrophysics
When Angela Olinto entered graduate school in physics at the Massachusetts Institute of Technology in 1982, there were two women and 60 men in her class. But over her 21 years at the University of Chicago, Olinto has welcomed 10 women and five men as graduate students into her research group, which specializes in particle astrophysics and cosmology.

"It's thrilling to look back and realize I've had about 70 percent women in my group, which is not something I planned," Olinto says. "It's been a colorful and brilliant group, lots of different nationalities and personalities, lots of different points of view. I've always learned as much from them as I taught them."

Olinto's students now have dispersed across the country and around the world. But many of them came together via email to nominate Olinto for the Faculty Award for Excellence in Graduate Teaching and Mentoring. Coordinating the effort was Olinto's current graduate student, Ke Fang, who graduates this summer.

"Independent of actually receiving the award, just the nomination itself was a great honor to me," Olinto says.


Related Links:
KICP Members: Angela V. Olinto
KICP Students: Ke Fang
Students in arts and sciences influence, benefit each other
The University of Chicago News Office, May 29, 2015
Benedikt Diemer (left), PhD candidate in astrophysics, and Isaac Facio, master of fine arts candidate at SAIC, collaborated on
Benedikt Diemer (left), PhD candidate in astrophysics, and Isaac Facio, master of fine arts candidate at SAIC, collaborated on "The Fabric of the Universe," a project that translated computer simulations of dark matter into 3-D textiles.
by Ryan Manzuk, The University of Chicago News Office

This year, in a new partnership with the School of the Art Institute of Chicago, the Arts, Science & Culture Initiative awarded grants to five teams composed of nine UChicago and three SAIC graduate students.

The goal of providing these collaborative grants is "to test the idea that different domains of knowing and knowledge -- arts, science and culture -- can enrich and influence each discipline's particular questions, tools, methodologies and specific curiosities," said Julie Marie Lemon, the program's director and curator.

The collaborative efforts between the students of arts, science and culture resulted in creative projects that were presented in early May.

One of the projects was "The Fabric of the Universe," created by Isaac Facio, a master of fine arts candidate in fiber and material studies at SAIC, and Benedikt Diemer, a UChicago PhD candidate in astrophysics. This project used computer simulations of dark matter and translated them into a more tangible form using three-dimensional textiles, resulting in a novel way of visualizing the structure of the universe.

Diemer said that the project has offered a new perspective for his research in astrophysics.

"Our project has caused me to look at my data in 3-D where I previously only made 2-D visualizations. This has definitely improved my understanding of the dark matter structures in my simulations," he said.

As a testament to the novel insights offered by this project, "'The Fabric of the Universe' was awarded a grant from the renowned TextielLab, part of the TextielMuseum, in Tilburg, the Netherlands, to produce the fabric," said Lemon, the program director.

And each year, Lemon noted, "the collaborations and the projects have become more and more sophisticated, and more students become interested in the initiative."


Related Links:
KICP Students: Benedikt Diemer
UChicago celebrates the promise of Chicago youth
The University of Chicago News Office, May 25, 2015
Daweed Abdiel, a KICP Space Explorer
Daweed Abdiel, a KICP Space Explorer
by Maureen Kelleher, The University of Chicago News Office

Though Daweed Abdiel always has been intellectually curious and a good student, college wasn't always on his radar. Most of his older family members had started college but never finished. In his first two years of high school, "I wasn't thinking about college too much," he said. "I was a good student, but I had no direction."

That changed after Abdiel joined the Upward Bound program offered through the Office of Special Programs-College Prep. Staff members who lead the program encouraged him to apply to colleges. "This program helped me determine I wanted a small liberal arts college." With Upward Bound showing the way, he got what he wanted. In August, Abdiel will attend Denison University with the support of two prestigious awards: a Gates-Millennium Scholarship and a Posse Scholarship.

"We have young people who develop a real sense of confidence and self-awareness about who they are and their ability to meet challenges and be successful," said Dovetta McKee, director of the Office of Special Programs-College Prep. "It changes their mindset about the leadership role they can play in their communities, and makes them models for young people who follow behind them," she said.

Abdiel was one of about 60 Chicago high school seniors honored at the 2015 Student Recognition Night, sponsored by the Office of Civic Engagement. The seniors took part in one of two programs: Upward Bound or the Collegiate Scholars Program, which prepares talented Chicago Public Schools students to succeed in the nation's top colleges and universities.

In addition, University students who have served with the Neighborhood Schools Program received recognition for their work in local public schools and community programs. All three efforts are part of UChicago Promise, the University's multi-pronged effort to increase college access and success for Chicago youth.

Increasing college access and success starts young. The Neighborhood Schools Program connects 375 UChicago students with 3,000 students in the surrounding neighborhoods. Many are still grade-schoolers, and tutoring can make a real impact on their future prospects.

"We leaned on NSP quite a lot and they came through," said Ed Kajor in a video shown at the event. Kajor, a learning behavior specialist at Burke Elementary in Washington Park, credits tutoring from volunteers like Amanda Weisler, a third-year sociology major, for boosting the school's scores on standardized tests.

"Our program is one of a few that is truly receptive to local school needs, said Shaz Rasul, director of community programs in the Office of Civic Engagement. "If a principal tells us she needs help with third grade, we will find tutors for the third grade who can be available during the school day. This is important because schools are often judged by what happens in the classroom, not enrichment time after school."

University students benefit, too. Real-world experience has led more than one NSP volunteer into a career in education, from Sara Stoelinga, who was honored at the event with the Don York Faculty Initiative Award, to keynote speaker Geoffrey Aladro AB'06, who is currently Miami-Dade's Teacher of the Year.

When Aladro discovered his long-held dream of corporate work wasn't all he thought it would be, he changed gears and chose teaching because of his NSP experiences. "I haven't really worked since I became a teacher," he told the crowd, "because I love my work."

Fourth-year Jonathan Fifer, who volunteered with NSP throughout his College career, intends to follow in their footsteps. His next goal will be to earn a master's degree from Teachers College, Columbia University, where he'll study early childhood education. "I've always been interested in the little kids," he said. "Even when they're crying or being bad, you can see their thought process. I can't be mad at them."

While teaching high school students about the college application process gets them started on their higher education journey, the Upward Bound and Collegiate Scholars programs also support young people's intellectual growth. Ivelise Colon, a Collegiate Scholar, has chosen Whittier College's alternative liberal arts program, where she will design her own major, incorporating elements of psychology, sociology and early childhood education. "I want to do my own thing," she said.

"The hallmark of Collegiate Scholars is the interaction with faculty. We are one of very few institutions in the country where there is intentional engagement between University faculty and public school students from across the city," said Abel Ochoa, interim director of the Collegiate Scholars Program. "It really elevates a student's frame of thinking to be taught by a professor who has written a textbook, done concrete research, or is considered a world-renowned expert in his field."

Like Colon, Abdiel has seen his intellectual interests shift over time, from physics to chemistry with a generous side helping of economics and African-American Studies. He credits his Upward Bound mentors for exposing him to the Kavli Institute of Cosmological Physics and for staying the course with him as his interests evolved. "They won't tell you what to do, but they'll ask you questions," he said. "They'll help you find your passions."


Related Links:
KICP Members: Randall H. Landsberg; Donald G. York
The Particle That Broke a Cosmic Speed Limit
Quanta Magazine, May 17, 2015
The Particle That Broke a Cosmic Speed Limit
by Natalie Wolchover, Quanta Magazine

Physicists are beginning to unravel the mysteries of ultrahigh-energy cosmic rays, particles accelerated by the most powerful forces in the universe.

In the night of October 15, 1991, the "Oh-My-God" particle streaked across the Utah sky.

A cosmic ray from space, it possessed 320 exa-electron volts (EeV) of energy, millions of times more than particles attain at the Large Hadron Collider, the most powerful accelerator ever built by humans. The particle was going so fast that in a yearlong race with light, it would have lost by mere thousandths of a hair. Its energy equaled that of a bowling ball dropped on a toe. But bowling balls contain as many atoms as there are stars. "Nobody ever thought you could concentrate so much energy into a single particle before," said David Kieda, an astrophysicist at the University of Utah.

Five or so miles from where it fell, a researcher worked his shift inside an old, rat-infested trailer parked atop a desert mountain. Earlier, at dusk, Mengzhi "Steven" Luo had switched on the computers for the Fly's Eye detector, an array of dozens of spherical mirrors that dotted the barren ground outside. Each of the mirrors was bolted inside a rotating "can" fashioned from a section of culvert, which faced downward during the day to keep the sun from blowing out its sensors. As darkness fell on a clear and moonless night, Luo rolled the cans up toward the sky.

"It was a pretty crude experiment," said Kieda, who operated the Fly's Eye with Luo and several others. "But it worked - that was the thing."

The faintly glowing contrail of the Oh-My-God particle (as the computer programmer and Autodesk founder John Walker dubbed it in an early Web article) was spotted in the Fly's Eye data the following summer and reported after the group spent an extra year convincing themselves the signal was real. The particle had broken a cosmic speed limit worked out decades earlier by Kenneth Greisen, Georgiy Zatsepin and Vadim Kuzmin, who argued that any particle energized beyond approximately 60 EeV will interact with background radiation that pervades space, thereby quickly shedding energy and slowing down. This "GZK cutoff" suggested that the Oh-My-God particle must have originated recently and nearby - probably within the local supercluster of galaxies. But an astrophysical accelerator of unimagined size and power would be required to produce such a particle. When scientists looked in the direction from which the particle had come, they could see nothing of the kind.

"It's like you've got a gorilla in your backyard throwing bowling balls at you, but he's invisible," Kieda said.

Where had the Oh-My-God particle come from? How could it possibly exist? Did it really? The questions motivated astrophysicists to build bigger, more sophisticated detectors that have since recorded hundreds of thousands more "ultrahigh-energy cosmic rays" with energies above 1 EeV, including a few hundred "trans-GZK" events above the 60 EeV cutoff (though none reaching 320 EeV). In breaking the GZK speed limit, these particles challenged one of the farthest-reaching predictions ever made. It seemed possible that they could offer a window into the laws of physics at otherwise unreachable scales - maybe even connecting particle physics with the evolution of the cosmos as a whole. At the very least, they promised to reveal the workings of extraordinary astrophysical objects that had only ever been twinkles in telescope lenses. But over the years, as the particles swept brushstrokes of light across sensors in every direction, instead of painting a telltale pattern that could be matched to, say, the locations of supermassive black holes or colliding galaxies, they created confusion. "It's hard to explain the cosmic-ray data with any particular theory," said Paul Sommers, a semiretired astrophysicist at Pennsylvania State University who specializes in ultrahigh-energy cosmic rays. "There are problems with anything you propose."

Only recently, with the discovery of a cosmic ray "hotspot" in the sky, the detection of related high-energy cosmic particles, and a better understanding of physics at more familiar energies, have researchers secured the first footholds in the quest to understand ultrahigh-energy cosmic rays. "We're learning things very rapidly," said Tim Linden, a theoretical astrophysicist at the University of Chicago.


Related Links:
KICP Members: Toshihiro Fujii; Tim Linden; Angela V. Olinto; Paolo Privitera
KICP Students: Ke Fang
Scientific projects: Pierre Auger Observatory (AUGER)