KICP Seminars & Colloquia, Spring 2012

Seminar schedule for Spring 2012
March 28, 2012
Wednesday colloquium
William Kinney
Univ. at Buffalo, SUNY
Inflation, or What?   [Abstract]
March 30, 2012
Friday noon seminar
Matthew Colless
Australian Astronomical Observatory
Expansion, acceleration and growth rate of the universe from the 6dF and WiggleZ surveys   [Abstract]
April 4, 2012
Astronomy Colloquium
Sarah Shandera
Pennsylvania State University
New Observational Handles on the Primordial Universe   [Abstract]
April 5, 2012
Friday noon seminar
Albert Stebbins
WYSIWYG Space-Time   [Abstract]
April 11, 2012
Wednesday colloquium
Laura Cadonati
University of Massachusetts Amherst
Probing the Transient Universe with Gravitational Waves   [Abstract]
April 13, 2012
Friday noon seminar
Rosalind E Skelton
Yale University
The rise of the red sequence: Exploring hierarchical growth with models and future prospects with the 3DHST and CANDELS surveys   [Abstract]
April 18, 2012
Astronomy Colloquium
Risa Wechsler
KIPAC/Stanford University
The Galaxy-Halo Connection Across Mass and Time   [Abstract]
April 20, 2012
Friday noon seminar
Will Percival
University of Portsmouth
First results from galaxy clustering in the BOSS survey   [Abstract]
April 25, 2012
Wednesday colloquium
Rachel Somerville
Rutgers University
The Other Side of Galaxy Formation: modeling gas in and around galaxies   [Abstract]
April 27, 2012
Friday noon seminar
Oliver Zahn
University of California, Berkeley
New Cosmology from the South Pole Telescope   [Abstract]
May 2, 2012
Astronomy Colloquium
Claudia de Rham
Case Western Reserve University
Massive Gravity and Cosmology   [Abstract]
May 3, 2012
Astronomy Special Seminar
David Arnett
Steward Observatory, University of Arizona
Stellar Turbulence, and why we should care   [Abstract]
May 4, 2012
Friday noon seminar
Reina Maruyama
University of Wisconsin-Madison
DM-Ice: a Search for Dark Matter at the South Pole   [Abstract]
May 9, 2012
Wednesday colloquium
John Beacom
Ohio State University
Diffuse Supernova Neutrino Background   [Abstract]
May 11, 2012
Friday noon seminar
Laura Newburgh
Princeton University
ACTPol: A Polarized Receiver for the Atacama Cosmology Telescope   [Abstract]
May 16, 2012
Astronomy Colloquium
Gil Holder
McGill University
Gravitational Lensing of the Cosmic Microwave Background   [Abstract]
May 18, 2012
Friday noon seminar
Vikram V Dwarkadas
University of Chicago
The Acceleration and Escape of Particles in Young Supernova Remnants   [Abstract]
May 23, 2012
Wednesday colloquium
Jonathan Feng
UC Irvine
Status of SUSY and SUSY Dark Matter   [Abstract]
May 30, 2012
Astronomy Colloquium
Mike Gladders
The University of Chicago
Through a Glass Darkly: Cluster Lensing Update 2012   [Abstract]

  • March 28, 2012 | 3:30 PM | BSLC 109 | Wednesday colloquium
    Inflation, or What?
    William Kinney, Univ. at Buffalo, SUNY

    Inflation has emerged as the leading model for the very early universe, not least because of the theory's remarkably successful prediction for the form of the CMB anisotropy. I ask the question: is inflation the only way to match the data? If not, what do the possible alternatives look like?
  • April 4, 2012 | 3:30 PM | BSLC 109 | Astronomy Colloquium
    New Observational Handles on the Primordial Universe
    Sarah Shandera, Pennsylvania State University

    Early universe cosmology is entering a new phase thanks to more precise measurements constraining the primordial density inhomogeneities. The Planck satellite and current and near future Large Scale Structure surveys are pursuing statistics of the inhomogeneities beyond the well-measured power spectrum. The potential of these new statistics has changed the way we think about theories of the primordial universe, including inflation. I will present the current understanding of how new data may decode the particle physics of inflation and provide more compelling tests of the theoretical framework for the primordial universe.
  • April 11, 2012 | 3:30 PM | BSLC 109 | Wednesday colloquium
    Probing the Transient Universe with Gravitational Waves
    Laura Cadonati, University of Massachusetts Amherst

    The Laser Interferometer Gravitational-wave Observatory (LIGO) and its sister project Virgo aim to achieve, within this decade, the first direct detection of gravitational waves and tune in to the gravitational-wave soundtrack of the Universe. The information from gravitational waves, complementary to the multi-wavelength electromagnetic spectrum, neutrinos and cosmic rays, will contribute to a more complete, understanding of some of the most violent and energetic events in the universe, such as gamma-ray bursts, soft-gamma repeaters, supernovae, and glitching pulsars. In this talk I will give an overview of ongoing efforts towards the realization of this new gravitational wave astrophysics, and of how electromagnetic and neutrino observations and the theoretical understanding of source dynamics are coupled into gravitational wave analysis. I will present selected results from the initial generation of LIGO and Virgo data and outline prospects for discovery in the advanced detector era, with particular focus on transient signatures.
  • April 18, 2012 | 3:30 PM | BSLC 109 | Astronomy Colloquium
    The Galaxy-Halo Connection Across Mass and Time
    Risa Wechsler, KIPAC/Stanford University

    Dark matter halos are the fundamental building blocks in the growth of structure and they provide the framework for our modern understanding of galaxy formation. I will discuss the current state of the art in our understanding of the connection between galaxy properties and their dark matter hosts over a range of masses and redshifts. In the context of a given cosmological model, I will show how the galaxy-halo relation can be tightly constrained at low redshift, and how it can be used to infer the full star formation histories of galaxies. This model for the co-evolution of galaxies and LCDM halos is in excellent agreement with a wide range of data, including the evolution of the stellar mass function, galaxy clustering statistics, and the statistics of satellites around Milky Way mass hosts. I will discuss applications to several issues in cosmology, including modeling of the faintest dwarfs and extracting cosmological constraints from the largest galaxy surveys.
  • April 25, 2012 | 3:30 PM | BSLC 109 | Wednesday colloquium
    The Other Side of Galaxy Formation: modeling gas in and around galaxies
    Rachel Somerville, Rutgers University

    Much observational work has focused on measuring the star formation rate in galaxies and its cosmic evolution. However, the supply rate of fuel for star formation (cold dense gas), the internal processes that regulate its conversion into stars, and the feedback processes that regulate star formation, all remain poorly understood both theoretically and observationally. I will discuss recent attempts to build more sophisticated theoretical models to predict the multi-phase gas content of galaxies, which in particular will allow us to make connections between galaxies as observed via stellar emission, emission in CO or HI, and in absorption.
  • May 2, 2012 | 3:30 PM | BSLC 109 | Astronomy Colloquium
    Massive Gravity and Cosmology
    Claudia de Rham, Case Western Reserve University

    Could the late-time acceleration of the Universe and the apparent discrepancy with standard particle physics be the first sign of the breakdown of gravity at very large distances? This is the question I will explore within the context of massive gravity. Whilst massive gravity is one of the earliest and most natural generalization of General Relativity, its fully consistent formulation was only unraveled recently. After discussing its realization I will explore its phenomenological implications, both on cosmological scales than within the solar system.
  • May 9, 2012 | 3:30 PM | BSLC 109 | Wednesday colloquium
    Diffuse Supernova Neutrino Background
    John Beacom, Ohio State University

    The Super-Kamiokande detector, shown here, is roughly 40 m in all directions. At any instant, it contains 10-100 neutrinos that were born in core-collapse supernovae across the cosmos. Can you spot them? Look for the red-and-white-striped sweaters.
    The diffuse supernova neutrino background (DSNB) is the weak glow of MeV neutrinos and antineutrinos from distant core-collapse supernovae. The DSNB has not been detected yet, but the Super-Kamiokande upper limit on the electron antineutrino flux is close to predictions, now quite precise, based on astrophysical data. If SK is modified with dissolved gadolinium to reduce detector backgrounds, then it should detect the DSNB at a rate of a few events per year, providing a new probe of supernova neutrino emission and the cosmic core-collapse rate. Neutrino astronomy, while uniquely powerful, has proven extremely difficult - only the Sun and the nearby Supernova 1987A have been detected to date - so the promise of detecting new sources soon is exciting indeed.
  • May 16, 2012 | 3:30 PM | BSLC 109 | Astronomy Colloquium
    Gravitational Lensing of the Cosmic Microwave Background
    Gil Holder, McGill University

    Gravitational lensing of the temperature and polarization anisotropies of the CMB is rapidly emerging as a new cosmological tool. Current experiments (as an example, I will focus on the South Pole Telescope) are using this effect to make mass maps over large areas. The power spectra of these mass maps allow new constraints on cosmological parameters, while the maps themselves can be cross-correlated with other tracers of the mass distribution to better understand the connections between mass and light.
  • May 23, 2012 | 3:30 PM | BSLC 109 | Wednesday colloquium
    Status of SUSY and SUSY Dark Matter
    Jonathan Feng, UC Irvine

    Weak-scale supersymmetry has long been a dominant paradigm for physics beyond the standard model and particle dark matter, but it is now being challenged by a wealth of experimental data. I will begin by reviewing attempts to quantify naturalness in supersymmetry, stressing the many subjective choices that impact the results both quantitatively and qualitatively. I then summarize experimental results that most directly challenge weak-scale supersymmetry, including recent results from the LHC. Some models are excluded or under great tension, while others remain perfectly viable. For the latter, I will outline the key features, current status, and implications for colliders and dark matter searches.
  • May 30, 2012 | 3:30 PM | BSLC 109 | Astronomy Colloquium
    Through a Glass Darkly: Cluster Lensing Update 2012
    Mike Gladders, The University of Chicago

    When I last spoke to the department in the fall of 2009, I gave an overview of several "work in progress" projects on strong lensing by galaxy cluster- and group-scale halos. In this 2012 update I will highlight the outcomes of these projects, focusing on three major themes: arc counts, the properties of lensing halos, and the lensed Universe. In the past few years, we have shown that, contrary to prior work, arc counts are in approximate agreement with theoretical expectations; the critical measurement to resolving this tension has been our measurement of the lensed source redshift distribution. In several related papers we have also measured the halo concentration distribution for large samples of lensing clusters and have shown that the previously dramatized 'over-concentration' problem in lensing clusters is at best about a 2-sigma effect. Parallel studies targeting the lensed background sources have revealed a wealth of new data on distant galaxies, probing new regimes of galaxy mass and star formation rates untouched by deep blank-field surveys, and revealing the detailed properties of individual galaxies with exquisite detail.


  • March 30, 2012 | 12:00 PM | LASR Conference Room | Friday noon seminar
    Expansion, acceleration and growth rate of the universe from the 6dF and WiggleZ surveys
    Matthew Colless, Australian Astronomical Observatory

    The 6dF Galaxy Survey has mapped 125,000 galaxies at a median redshift z=0.05 over the whole southern hemisphere, while the WiggleZ survey has mapped 220,000 star-forming galaxies at redshifts out to z=1 over a cubic gigaparsec. In combination, these surveys measure the evolution of the power spectrum of the galaxy distribution, including the features due to the baryon acoustic oscillations and redshift-space distortions. These measurements yield the expansion history of the universe over the last 8 billion years, and provide new and model-independent determinations of the Hubble constant at low redshift, the rate of acceleration since z=1, and the growth of large-scale structure. They also give an improved upper limit on the sum of the neutrino masses.
  • April 5, 2012 | 12:00 PM | LASR Conference Room | Friday noon seminar
    WYSIWYG Space-Time
    Albert Stebbins, Fermilab

    An observationally based, non-perturbative approach to learning about the space-time geometry of our universe. On macroscopic scales new forces are determined by measuring accelerations e.g. Newton and Kepler for gravity, or balancing known with unknown forces in a static configuration. Dark energy is a putative gravitationally repulsive substance which permeates our universe, yet the evidence for it involves neither technique, but is rather a mix of observations and assumptions about the geometry of space-time and initial conditions. In fact much of cosmology is done this way. Here I examine what one can learn about space-time geometry purely by observations from a single vantage point of distant objects and their motions and, in particular, not assuming the cosmological principle. A formalism is developed whereby all of space-time geometry is expressed in terms of observables. Some new and interesting formulae are derived and a possible future path for dark energy studies is given.
  • April 13, 2012 | 12:00 PM | LASR Conference Room | Friday noon seminar
    The rise of the red sequence: Exploring hierarchical growth with models and future prospects with the 3DHST and CANDELS surveys
    Rosalind E Skelton, Yale University

    A major merger observed with the 3D-HST survey.
    The massive quiescent galaxies we see at low redshifts seem to evolve slowly and passively, having formed at high redshift. The role of mergers in their formation and growth is strongly debated, as there does not seem to be much room for growth based on the observed luminosity evolution. I will describe the simple models we have used to test how hierarchical growth affects red sequence galaxies from z=1 to z=0. We find that the changes in color and luminosity for a population that builds up through mergers are very similar to those of an old, passively evolving population, but imply very different mass growth. The observed evolution can be equally well explained as the result of hierarchical growth. I will discuss how the large new surveys 3DHST and CANDELS will extend our understanding of the role of mergers and the build up of bulges to lower masses and out to higher redshifts.
  • April 20, 2012 | 12:00 PM | LASR Conference Room | Friday noon seminar
    First results from galaxy clustering in the BOSS survey
    Will Percival, University of Portsmouth

    First results are presented from galaxy clustering measurements in the Baryon Oscillation Spectroscopic Survey (BOSS), which is part of SDSS-III. Data release 9, due for public release in July, contains 327,349 massive galaxies with an effective redshift z=0.57 covering 3,275 square degrees. Assuming a concordance LCDM cosmological model, this is equivalent to 0.77 h^{-3} Gpc^3, and represents the largest sample of the Universe ever surveyed at this density. I will present results including Baryon Acoustic Oscillation (BAO), Redshift-Space Distribution (RSD) measurements, and cosmological constraints from full fits to the clustering signal. In particular, including the BAO measurements alongside previous measurements, results in a BAO distance ladder, which will be compared to current supernovae measurements.
  • April 27, 2012 | 12:00 PM | LASR Conference Room | Friday noon seminar
    New Cosmology from the South Pole Telescope
    Oliver Zahn, University of California, Berkeley

    I will talk about two ongoing cosmological revolutions that are fueled by high angular resolution and high sensitivity observations of the Cosmic Microwave Background: constraining the properties of the first sources of radiation in the universe via the kinetic Sunyaev-Zel'dovich effect, and constraining astroparticle and gravitational physics via lensing of the CMB. I will report on the status and prospects of these endeavors.
  • May 4, 2012 | 12:00 PM | LASR Conference Room | Friday noon seminar
    DM-Ice: a Search for Dark Matter at the South Pole
    Reina Maruyama, University of Wisconsin-Madison

    I will describe DM-Ice, a proposed dark matter experiment at the South Pole. The aim of the experiment is to test the claim for an observation of dark matter by the DAMA collaboration by carrying out an experiment with the same detector technology, but in the southern hemisphere. By going to the opposite hemisphere, many of the suspected backgrounds would produce annual modulation with the opposite phase whereas the dark matter signature should stay the same. A 17-kg detector was installed in the Antarctic ice at the South Pole in December 2010 and is currently taking data. The full-scale experiment that can test DAMA's claim is currently being designed. I will report on the status of DMIce-17 and the plans for the full-scale experiment.
  • May 11, 2012 | 12:00 PM | LASR Conference Room | Friday noon seminar
    ACTPol: A Polarized Receiver for the Atacama Cosmology Telescope
    Laura Newburgh, Princeton University

    ACTPol is a ground-based experiment designed to measure the polarization of the Cosmic Microwave Background at arcminute scales. The ACTPol receiver will feature three independent arrays each with ~1000 polarization-sensitive feedhorn-coupled TES bolometers, giving a factor of ~4 improvement in sensitivity compared to the existing receiver for the 6m Atacama Cosmology Telescope (ACT). Our observation strategy will include survey regions chosen to overlap with other multi-frequency surveys. The resulting combination of sensitive maps enables a wide range of measurements and cosmological constraints including the spectrum from gravitational lensing, the sum of the neutrino masses, the number of relativistic species, the spectral shape of the primordial power spectrum, and the primordial helium abundance, along with many more. I will present an instrument overview, science goals, and the status of the first array, set to deploy this year.
  • May 18, 2012 | 12:00 PM | KPTC 206 (Note Location) | Friday noon seminar
    The Acceleration and Escape of Particles in Young Supernova Remnants
    Vikram V Dwarkadas, University of Chicago

    The acceleration of high-energy particles to relativistic energies is a long-standing problem that has been highlighted in recent times, with the growth of various gamma-ray and cosmic ray facilities, and the Fermi space telescope. Of particular importance are the properties of the accelerator and their relation to the spectrum of accelerated particles, and the energies to which particles are accelerated. Combining numerical simulations of supernova remnant (SNR) evolution with a solution of the cosmic-ray transport equation in test-particle mode, we study the acceleration of particles at forward and reverse shocks in both Type Ia and core-collapse SNRs. We include the effect of various magnetic field profiles in the shocked interaction region. We study the temporal evolution of the non-thermal particle distribution, and synthesize surface brightness maps for various radiation mechanisms. We investigate how the spectrum of escaped particles depends on the time-dependent acceleration history in young SNRs, and calculate the time-dependent gamma-ray spectra from molecular clouds illuminated by the escaping cosmic-rays. We also study the maximum energy of the escaped particles, and its evolution with time, and provide analytic approximations for the same.


  • May 3, 2012 | 2:00 PM | LASR Conference Room | Special Seminar
    Stellar Turbulence, and why we should care
    David Arnett, Steward Observatory, University of Arizona

    Supercomputers allow the simulation of three-dimensional highly turbulent flow. Treating these numerical "experiments" as valid representations of the behavior of high energy density (HED) plasma, a view supported by laboratory experiments with inertial confinement fusion (ICF) devices, we are beginning to develop a theory of this behavior appropriate to stellar interiors. Unlike conventional astrophysical convection theory, the Richardson-Kolmogorov turbulent cascade and the Lorenz strange attractor make an appearance, as well as a rich set of boundary-region physics. The process of developing physical insight from numerical simulations will be illustrated, and implications for stellar evolution, from the Sun to gamma-ray bursts and supernovae, will be discussed.