The Halo Boundary of Galaxy Clusters in SDSS
April 24, 2017
The existence of such physical edges associated with sharp density drops due to the density caustics formed by accreting matter was predicted by KICP researchers Benedikt Diemer and Andrey Kravtsov in 2014, as part of Diemers PhD research. In a follow-up study, Diemer, Kravtsov and a former KICP fellow Surhud More (currently at Institute of Physics of the Universe, Tokyo, Japan) have shown that the-edges can be considered to be natural physical boundary of dark matter halos that provide the gravitational "back-bone" for the structures observed in the galaxy distribution.
In the recent study, co-led by Chihway Chang and Eric Baxter - a former KICP student and currently a postdoctoral fellow at the University of Pennsylvania - the density drop associated with the halo edges was detected in the galaxy distribution around cluster centers.
Cosmological simulations show that massive galaxy clusters we see today have been accreting galaxies into their deep gravitational potential over the cosmic time. The process of galaxies "falling into" the cluster's potential well is a fairly clean and universal process that depends only on basic quantities of the cluster such as mass and accretion rate. One of the result of this simple picture is a sharp feature in the number density of galaxies around clusters - an imprint of the caustic formed by the infalling galaxies as they reach the first apocenter of their orbit, or the "edge" of the galaxy cluster. Researchers called the distance of the edge the "splashback" radius, as galaxies literally "splashing back" to that radius after they accrete onto cluster.
Together with collaborators in UPenn and UIUC, that included KICP faculty Andrey Kravtsov, Chihway Chang and Eric Baxter, examined distribution of galaxies around a sample of clusters identified within the SDSS. The existence of the edge in the galaxy distribution within clusters was confirmed. In addition, the analysis revealed that properties of galaxies around cluster are sensitive to existence of the edge. Outside the splashback radius, the mix of red and blue galaxies was approximately independent of the distance from the cluster center, while inside the splashback radius the mix is abruptly changes towards a larger fraction of red galaxies. This indicates that the edge is a real dynamical feature and that majority of galaxies get transformed by the cluster environment from blue to red in less than one orbital period.
This figure shows the fraction of red and blue galaxies around galaxy clusters. The sharp change in the red fraction indicates that galaxy tend to turn red once they enter the edge of the cluster, which is marked by the grey vertical band. (Figure modified from the paper "The Halo Boundary of Galaxy Clusters in the SDSS".)
Related KICP references:
KICP Members: Chihway Chang; Andrey V. Kravtsov; Surhud More
KICP Students: Eric J. Baxter; Benedikt Diemer; Phil Mansfield
The Event Horizon Telescope's historic quest
April 13, 2017
KICP Members: Bradford A. Benson; John E. Carlstrom
Scientific projects: South Pole Telescope (SPT)
Abigail Vieregg will receive the 2017 Shakti P. Duggal Award
March 27, 2017
KICP Members: Abigail G. Vieregg
Prof. Angela Olinto has been awarded a NASA grant for "Concept Study of the Probe Of Extreme Multi Messenger Astrophysics (POEMMA)"
March 20, 2017
The team will receive funds for an 18-month comprehensive study.
KICP Members: Angela V. Olinto
Scientific projects: Pierre Auger Observatory (AUGER)
The KICP will welcome 5 new Fellows in the Autumn of 2017
March 9, 2017
Macarena Lagos will receive her PhD from Imperial College London. Her research focuses on theoretical cosmology, specifically on analysing the viability of alternative gravity theories and developing methods to test gravity at large scales. At KICP, Macarena hopes to continue her current research and start new collaborations with its members.
Kirit Karkare will join us as a joint Grainger and KICP Fellow after completing his degree at Harvard University, where he worked on hardware and systematics analysis for the BICEP/Keck CMB polarization experiments. At the KICP, he plans to continue working on the CMB with BICEP and SPT, and on detector development for line intensity mapping and measurements of high-redshift galaxies.
Wai Ling (Kimmy) Wu did her graduate work at Stanford University with the BICEP/Keck team on the design, testing, and deployment of BICEP3 -- a small aperture CMB polarimeter that aims to target the inflationary gravitational wave B-mode signature. She then moved to UC Berkeley to work with the SPT team on the SPT-3G receiver and on delensing CMB B-mode maps, an important step to further constraint the inflationary B-mode signature. At KICP, she plans on extending her delensing work with BICEP/Keck and SPT datasets and looks forward to exploring new avenues to understand the cosmos with fellow KICP researchers.
Grayson Rich carried out research at Triangle Universities Nuclear Laboratory (TUNL) while a graduate student at the University of North Carolina. As a part of the COHERENT Collaboration, he has been working towards the first observation of coherent, elastic neutrino-nucleus scattering (CEvNS): a low-energy neutrino-nucleus interaction arising from the standard model but still undetected over 40 years after its prediction. As a KICP Fellow and an Enrico Fermi Fellow at the Enrico Fermi Institute, he will maintain involvement with COHERENT and continue to advance an effort he spearheaded at TUNL to provide definitive characterizations of the responses of neutrino and dark matter detector systems, working with several groups at KICP and the broader astroparticle physics community. He also hopes to work with KICP and EFI members to exploit high-energy astrophysical signals, seeking insight into cosmological questions and the properties of fundamental particles.
Scientific projects: BICEP2/The Keck Array/BICEP3; South Pole Telescope (SPT)
Hsin-Yu Chen has been selected for a Cronin Fellowship
February 15, 2017
Angela V. Olinto,
Homer J. Livingston Professor and Chair Department of Astronomy & Astrophysics
KICP Members: Daniel E. Holz; Angela V. Olinto
KICP Students: Hsin-Yu Chen
Deflategate: Cold Wet Footballs, Ideal Gas Laws and Accusations of Cheating
February 8, 2017
Twenty-eight (28) high school students in KICP's Space Explorers program put these arguments to the test. Over the course of two weeks, students critically evaluated over a dozen arguments made by both sides, ranging from court documents, to college lectures, to tweets. Despite the strong opinions, contradictory claims, and often factually incorrect information found in these arguments, the Space Explorers managed to identify the critical questions that needed to be resolved to determine if Deflategate could be caused by purely innocuous physics and designed an experiment to address them. Their experiment revolved around measuring the effect that wetness had on the rate at which cold footballs warm up and increase in pressure.
To date their results are inconclusive. One trial found nothing suspicious about the pressure drop, and a second could not explain the low pressures in the Patriots' footballs. The Space Explorers themselves are split down the middle about how to interpret their results and will debate the best way to resolve this difference at the pre-Super Bowl Saturday class.
KICP Students: Phil Mansfield
Summer Undergraduate Researcher Michael Foley Wins AAS Chambliss Student Medal
February 1, 2017
KICP Members: Richard Kessler; Daniel Scolnic
Former KICP Fellow Eric Dahl honored with a PECASE
January 24, 2017
Scientific projects: COUPP/PICO
On MLK Day King College Prep Cosmology Club Explores Dark Matter
January 16, 2017
KICP Members: Luca Grandi
Space Explorer Naa Ashitey is the Quest Bridge Finalist for the University of Chicago
December 12, 2016
QuestBridge is a nonprofit program designed to assist high-achieving, academically motivated students from low-income backgrounds apply to top colleges around the nation. The program features the National College Match, in which students rank and apply to up to eight of QuestBridge's partner colleges. Students who are matched receive a generous four-year, no-loan scholarship.
KICP Members: Randall H. Landsberg
Mark SubbaRao to become IPS President-Elect
December 7, 2016
Mark SubbaRao won the recent International Planetarium Society (IPS) election and will assume the role of President-Elect of this prestigious society at the beginning of 2017. In two year's time he will become the President of the IPS for a two year term.
In his candidate's statement, Mark said "I am running for IPS President to help shape the future of the planetarium, this wonderful medium which can inspire the public like nothing else.
... If elected, I will focus on building a more active organization and expanding professional development opportunities. We will support research that demonstrates how effective the planetarium is."
Read the entire statement at the International Planetarium Society website.
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KICP Members: Mark Subbarao
The Long Duration Balloon season has begun
December 2, 2016
KICP members working on the project include Abby Vieregg, postdoctoral researchers Cosmin Deaconu and Eric Oberla, and graduate student Andrew Ludwig. Cosmin, Eric, and Andrew are in Antarctica for the integration, testing, launch, and flight.
KICP Members: Cosmin Deaconu; Eric Oberla; Abigail G. Vieregg
KICP Students: Andrew Ludwig
Scientific projects: Antarctic Impulsive Transient Antenna (ANITA)
Chicago high school students visit to experience "A day in the life of a scientist"
November 15, 2016
As part of her activities, Professor Freedman recently arranged for students to visit the Eckhardt Research Center for a discussion and tour of the KICP and Astronomy & Astrophysics labs and the Pritzker Nanofabrication Facility. Students visited the PNF and the KICP labs of Professor Erik Shirokoff (where Associate Fellow Peter Barry described the lab equipment and activities), and gathered in Professor Stephan Meyer's lab to see a camera that will be used in a balloon-borne experiment to detect cosmic ray showers. Professors Meyer and Freedman also spoke to students about various aspects of their research and their lives as scientists.
Professor Meyer explains Extensive Air Showers to the visiting students.
Stephan Meyer showing the visitors around his lab.
Associate Fellow Peter Barry explaining a piece of apparatus in the Shirokoff lab.
KICP Members: Peter Barry; Wendy L. Freedman; Stephan S. Meyer; Erik Shirokoff
SPT-3G Camera Has Shipped to the South Pole
November 1, 2016
KICP Members: Amy Bender; Bradford A. Benson; Lindsey Bleem; John E. Carlstrom; Clarence L. Chang; Thomas M. Crawford; Stephan S. Meyer; Stephen Padin; Erik Shirokoff
Scientific projects: South Pole Telescope (SPT)
Congratulations to Robert Wald!
October 20, 2016
KICP Members: Robert M. Wald
Congratulations to Scott Wakely!
October 13, 2016
KICP Members: Scott P. Wakely
Scientific projects: Very Energetic Radiation Imaging Telescope Array System (VERITAS)
Congratulations to Matthew Richardson, KICP Fisk-Vanderbilt Bridge Program participant!
October 10, 2016
"Through a careful analysis of data collected by the MIDAS detector installed at the Pierre Auger Observatory, Matt has established the best limits on microwave emission from Extensive Air Showers induced in the atmosphere by Ultra-High Energy Cosmic Rays (UHECR). His results, an improvement by more than one order of magnitude over previously published limits, place strong constraints on the prospects of this technique for UHECR detection."
- Paolo Privitera
Matt has received a position of Postdoctoral Research Scientist at the Planetary Science Institute.
KICP Members: Paolo Privitera
Scientific projects: Microwave Detection of Air Showers (MIDAS)
"Bruce Winstein", biographical memoir by Mel Sochet and Michael Turner
September 27, 2016
2016 Yerkes Summer Institute: Spy vs. Spy
August 16, 2016
The 2016 Yerkes Summer Institute (YSI) was filled with secrecy, deception, and espionage. At YSI, high school students in the Space Explorers program played the role of 20th-Century spies to handle secret information: revealing, concealing and distorting information. Through three day-long lab activities, the students explored connections between spying and science. In the "Secret Photos" lab, they studied angular size, resolution, and the film-development process in order to effectively gather information on "enemy operatives" using 35 mm cameras. In the "Radio Beams" lab, students designed, built, and tested a system to transmit audio via an amplitude-modulated (AM) laser, which allowed them to secretly communicate across long distances. Lastly, techniques to securely communicate were examined in the "Codes and Ciphers" lab, which also served as an introduction to modern cryptography. After cycling through these three day labs, the students broke into three new groups and took one of the labs a step further: one group doctored photographs to spread false information, another built AM radio transmitters and receivers, and the last created treasure hunts using codes and ciphers for the clues. Nighttime activities included: observations with the Yerkes telescopes, astrophotography, explorations of the constellations which focused on what current research can tell us about them (e.g. most know exoplanets were found by Kepler in the constellation Cygnus); and bad weather activities that included examinations of the veracity of viral internet photos, and stories of famous spies. The week's spy-themed activities not only introduced the students to the importance of privacy in the digital age, but also to the concepts and skills that are integral to any modern STEM career.
KICP Members: Camille Avestruz; Richard G. Kron; Randall H. Landsberg
KICP Students: Zoheyr Doctor; Gourav Khullar; James Lasker; Phil Mansfield; Jason Poh
Congratulations to Dr. Sean Johnson!
July 18, 2016
"Sean's thesis work casts new light on the intricate physical processes that drive the baryon cycles between star-forming regions and the intergalactic space. He led an ambitious survey of the galactic environments around chemically-enriched gas revealed in strong absorption against a background source. Sean's thesis sample represents the first of its kind in terms of both the scale and depth of galaxy survey data in quasar fields. It provides a pathfinder for future large-scale studies that will combine wide-field galaxy surveys with absorption spectroscopy to advance our understanding of chemical enrichment in low-density regions away from galaxies."
- Hsiao-Wen Chen, PhD advisor
Sean will be starting as a Carnegie-Princeton/Hubble fellow at Princeton in the fall.
KICP Members: Hsiao-Wen Chen
KICP Students: Sean Johnson
Congratulations to Dr. Asher Berlin!
July 8, 2016
"Asher's work has covered a broad range of topics related to dark matter and efforts to reveal its particle nature. He has worked on theory calculations relevant to underground and space-based dark matter searches and to searches for dark matter at the Large Hadron Collider. More recently, he has worked on non-standard ways in which dark matter may be have created in the early universe."
- Dan Hooper, PhD advisor
Asher has received a Post Doctoral Fellow position at SLAC.
KICP Members: Daniel Hooper; Lian-Tao Wang
KICP Students: Asher Berlin
Congratulations to Dr. Jonathan Richardson!
June 23, 2016
"Jon's thesis represents an important milestone. He's done much of the critical work to make the Holometer experiment a reality. It's the most sensitive instrument ever built to study tiny random jitters of space. In his thesis, he shows that the scale of random shear jitter is more than an order of magnitude less than the Planck length, which was the theoretical expectation. The experiment essentially rules out this effect. He's working with our team now to reconfigure the machine to study the other possibility, a jitter of rotational motion, at similar sensitivity. There is some hope that this effect in the laboratory may connect with the cosmic dark energy problem."
- Craig J. Hogan
Jonathan has received a Research Fellow position at the University of Michigan.
KICP Members: Craig J. Hogan; Stephan S. Meyer
KICP Students: Jonathan Richardson
Congratulations to Dr. Brittany Kamai!
June 22, 2016
"Brittany's thesis uses the Holometer data for a unique measurement of gravitational waves in the Megahertz frequency band. Her analysis sets limits on possible exotic sources of gravitational waves, such as black holes in binaries of very small mass -- radiating at frequencies ten thousand time higher than those recently measured by LIGO."
- Craig J. Hogan
Brittany has received a position of LIGO Instrumentation Postdoctoral Fellow at the California Institute of Technology.
KICP Members: Craig J. Hogan; Stephan S. Meyer
KICP Students: Brittany Kamai
The 2016 Kavli Prizes
June 2, 2016
This year's laureates were selected for the direct detection of gravitational waves, the invention and realization of atomic force microscopy, and for the discovery of mechanisms that allow experience and neural activity to remodel brain function.
The Kavli Prize in Astrophysics goes to Ronald W.P. Drever, Kip S. Thorne and Rainer Weiss. Gerd Binnig, Christoph Gerber and Calvin Quate share the Kavli Prize in Nanoscience. The Kavli Prize in Neuroscience goes to Eve Marder, Michael Merzenich and Carla Shatz.
The Kavli Prize is awarded by The Norwegian Academy of Science and Letters and consists of a cash award of 1 million US dollars in each field. The laureates receive in addition a gold medal and a scroll. Today’s announcement was made by Ole M. Sejersted, President of the Norwegian Academy of Science and Letters, and transmitted live to New York as part of a World Science Festival event where France Cordova, Director of the National Science Foundation, delivered the keynote address.
The Kavli Prize in Astrophysics is shared between Ronald W.P. Drever and Kip S. Thorne, both from the California Institute of Technology, USA, and Rainer Weiss of the Massachusetts Institute of Technology, USA. They receive the prize "for the direct detection of gravitational waves".
The signal picked up by the Laser Interferometer Gravitational-wave Observatory (LIGO) in the US on September 14, 2015, lasted just a fifth of a second but brought to an end a decades-long hunt to directly detect the ripples in space-time known as gravitational waves. It also opened up a completely new way of doing astronomy, which uses gravitational rather than electromagnetic radiation to study some of the most extreme and violent phenomena in the universe.
This detection has, in a single stroke and for the first time, validated Einstein’s General Theory of Relativity for very strong fields, established the nature of gravitational waves, demonstrated the existence of black holes with masses 30 times that of our sun, and opened a new window on the universe.
The detection of gravitational waves is an achievement for which hundreds of scientists, engineers and technicians around the world share credit. Drever, Thorne and Weiss stand out: their ingenuity, inspiration, intellectual leadership and tenacity were the driving force behind this epic discovery.
The Kavli Prize in Nanoscience is shared between Gerd Binnig, Former Member of IBM Zurich Research Laboratory, Switzerland, Christoph Gerber, University of Basel, Switzerland, and Calvin Quate, Stanford University, USA. They receive the prize "for the invention and realization of atomic force microscopy, a breakthrough in measurement technology and nanosculpting that continues to have a transformative impact on nanoscience and technology".
The realization of the atomic force microscope was reported by Binnig, Gerber and Quate in 1986, with a demonstration that the instrument could be used to obtain profiles of a solid-state surface with close to atomic resolution.
In the last 30 years the instrument has evolved dramatically and has provided fundamental insight into the chemistry and physics of a large variety of surfaces. It is still widely used today as a versatile tool for imaging and manipulation in a broad range of scientific disciplines.
The Kavli Prize in Neuroscience is shared between Eve Marder, Brandeis University, USA, Michael Merzenich, University of California San Francisco, USA, and Carla Shatz, Stanford University, USA. They receive the prize "for the discovery of mechanisms that allow experience and neural activity to remodel brain function".
Until the 1970s, neuroscientists largely believed that by the time we reach adulthood the architecture of the brain is hard-wired and relatively inflexible. The ability of nerves to grow and form abundant new connections was thought mainly to occur during infancy and childhood. This view supported the notion that it is easier for children to learn new skills such as a language or musical instrument than it is for adults.
Over the past 40 years, however, the three Kavli neuroscience prize-winners have challenged these assumptions and provided a convincing view of a far more flexible adult brain than previously thought possible - one that is 'plastic', or capable of remodelling. Working in different model systems, each researcher has focused on how experience can alter both the architecture and functioning of nerve circuits throughout life, given the right stimulus and context. They have provided a physical and biochemical understanding of the idea of 'use it, or lose it'.
This new picture of a more adaptable brain offers hope for developing new ways to treat neurological conditions that were once considered untreatable.
About the Kavli Prizes
The Kavli Prize is a partnership between the Norwegian Academy of Science and Letters, The Kavli Foundation (USA) and the Norwegian Ministry of Education and Research. The Kavli Prizes were initiated by and named after Fred Kavli (1927-2013), founder of The Kavli Foundation, which is dedicated to advancing science for the benefit of humanity, promoting public understanding of scientific research, and supporting scientists and their work.
Kavli Prize recipients are chosen biennially by three prize committees comprised of distinguished international scientists recommended by the Chinese Academy of Sciences, the French Academy of Sciences, the Max Planck Society, the U.S. National Academy of Sciences and the Royal Society.
After the prize committees have selected the award recipients, their recommendations are confirmed by the Norwegian Academy of Science and Letters.
The 2016 Kavli Prizes will be awarded in Oslo, Norway, on 6 September. His Royal Highness Crown Prince Haakon will present the prizes to the laureates. This year's ceremony will be hosted by Alan Alda and Lena Kristin Ellingsen. Prime Minister Erna Solberg will host a banquet at Oslo City Hall in honour of the laureates.
The ceremony is part of Kavli Prize Week - a week of special programmes to celebrate extraordinary achievements in science.
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Congratulations to Prof. Angela V. Olinto!
May 31, 2016
KICP Members: Angela V. Olinto
Keith Bechtol wins Saturday's Soldier Field 10 Mile Race
May 31, 2016
Dan Scolnic Competes in Famelab national finals
May 18, 2016
FameLab USA is a NASA-sponsored, science-based take on American Idol, aimed at fostering an open community for science communication and development.
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KICP Members: Daniel Scolnic
Wayne Hu elected to the National Academy of Sciences
May 3, 2016
Wayne Hu is a senior member of the KICP and the Horace B. Horton Professor in the Department of Astronomy & Astrophysics, Enrico Fermi Institute, and the College. His research focuses on the theory and phenomenology of structure formation in the Universe as revealed in Cosmic Microwave Background anisotropies, gravitational lensing, galaxy clustering and galaxy clusters.
KICP Members: Wayne Hu