KICP Seminars & Colloquia, Current and Future
Today's Seminar
Upcoming Seminars

Seminar schedule for Current (Spring 2016) & Future Quarters
April 1, 2016
Friday noon seminar
Miguel Zumalacarregui
Nordic Institute for Theoretical Physics
Gravity at the horizon: from the cosmic dawn to ultra-large scales   [Abstract | PDF]
April 5, 2016
Astronomy Tuesday Seminar
Andrew Hearin
Yale University
Modeling Galaxies in the Era of Precision Cosmology: A community-driven approach with Halotools   [Abstract]
April 6, 2016
Astronomy Colloquium
James Stone
Princeton University
Global Radiation MHD Simulations of Black Hole Accretion Disks   [Abstract]
April 8, 2016
Friday noon seminar
John M Kearney
Fermi National Accelerator Laboratory
High-Scale Axions without Isocurvature from Inflationary Dynamics   [Abstract]
April 13, 2016
Wednesday colloquium
Jacqueline Hewitt
MIT
Probing the Cosmic Dawn and the Epoch of Reionization with the 21cm Hydrogen Line   [Abstract]
April 15, 2016
Friday noon seminar
Dan Scolnic
The University of Chicago
A New Measurement of the Hubble Constant   [Abstract]
April 20, 2016
Astronomy Colloquium
Eliot Quataert
UC Berkeley
The Dynamic Last Years in the Lives of Massive Stars   [Abstract]
April 22, 2016
Friday noon seminar
Colin Hill
Columbia University
More Is Different: The Power of Multi-Probe CMB/LSS Cross-Correlations   [Abstract]
April 27, 2016
Wednesday colloquium
Paolo Privitera
KICP/The University of Chicago
WIMPs taking selfies: the DAMIC experiment at SNOLAB   [Abstract | PDF | Video]
May 3, 2016
Astronomy Tuesday Seminar
Ilse Cleeves
Harvard CfA
Fire and Ice: The role of energetic processes in the cold chemistry of planet-forming circumstellar disks   [Abstract]
May 4, 2016
Astronomy Colloquium
David W Hogg
New York University
A data-driven model of stars   [Abstract]
May 6, 2016
Friday noon seminar
Francis-Yan Cyr-Racine
Harvard University
ETHOS – From Dark Particle Physics to the Matter Distribution of the Universe and Beyond   [Abstract]
May 11, 2016
Wednesday colloquium
Jordan Goodman
Maryland
Results from the first year of the HAWC Gamma Ray Observatory   [Abstract]
May 13, 2016
Friday noon seminar
Mariangela Lisanti
Princeton University
Resolving the Isotropic Gamma-Ray Background in the Search for Dark Matter   [Abstract]
May 18, 2016
Astronomy Colloquium
Tiziana Di Matteo
Carnegie Mellon University
TBA
May 19, 2016
Astronomy Special Seminar
Joan Schmelz
Arecibo Observatory; Universities Space Research Association
TBA
May 20, 2016
Friday noon seminar
Blake D Sherwin
University of California, Berkeley
CMB Lensing Measurements, Present and Future
May 24, 2016
Astronomy Tuesday Seminar
Jonathan Stern
Max Planck Institute for Astronomy (Heidelberg, Germany)
TBA
May 25, 2016
Astronomy Colloquium
Anna Frebel
MIT, Kavli Institute for Astrophysics and Space Research
A single prolific r-process event preserved in an ultra-faint dwarf galaxy   [Abstract]
June 3, 2016
Friday noon seminar
Lauren M Pearce
University of Minnesota & Valparia
Higgs Relaxation Leptogenesis
 
WEDNESDAY COLLOQUIA
KICP Wednesday Colloquia: Unless otherwise noted, all talks are held in ERC 161 at 3:30 PM on Wednesdays. A reception will be held in the ERC 161 following the talk.

  • April 13, 2016 | 3:30 PM | ERC 161
    Probing the Cosmic Dawn and the Epoch of Reionization with the 21cm Hydrogen Line
    Jacqueline Hewitt, MIT

    Measurements of the cosmic microwave background at redshift z ~ 1100 give us information about the initial density fluctuations that seeded subsequent gravitational collapse and structure formation. Observations of galaxies and clusters at z <~ 7 give us information about the outcome of this structure formation. Between those redshifts lies a modern frontier of cosmology - the cosmic dawn that marked the formation of the first stars and galaxies and the deionization of the intergalactic medium. Direct observations of this phase of the universe's history are just beginning. A particularly promising technique is that of mapping hydrogen structures using the redshifted 21cm radio line. Several recently completed low frequency radio arrays are now operating and providing us with an early glimpse into the Epoch of Rionization. Building upon these results a next generation instrument, the Hydrogen Epoch of Reionization Array (HERA) is beginning construction. HERA will be significantly more capable, and presents interesting opportunities and challenges.
  • April 27, 2016 | 3:30 PM | ERC 161
    WIMPs taking selfies: the DAMIC experiment at SNOLAB
    Paolo Privitera, KICP/The University of Chicago

    Many tracks
    PDF | Video
    The DAMIC (Dark MAtter In CCDs) experiment employs the bulk silicon of ~mm-thick charge-coupled devices (CCDs) to detect coherent elastic scattering of Weakly-Interacting Massive Particles (WIMPs) - putative yet-to-be-discovered particles which may explain the dark matter in the universe. This novel technique features an unprecedentedly low energy threshold (few tens of eVee) for the detection of nuclear recoils, providing optimal sensitivity for low mass WIMPs (< 10 GeV). In addition, the spatial resolution of the CCDs, unique amongst dark matter detectors, provides powerful methods to identify and mitigate environmental and cosmogenic backgrounds. I will show recent results from DAMIC R&D data which demonstrate the potential of the CCD technology for WIMP detectors and first images from DAMIC100, a 100 g detector with 18 CCDs under installation at SNOLAB.
  • May 11, 2016 | 3:30 PM | ERC 161
    Results from the first year of the HAWC Gamma Ray Observatory
    Jordan Goodman, Maryland
    Note: Reception at 4:30 PM in the ERC 161.

    The High Altitude Water Cherenkov (HAWC) Gamma-ray Observatory in the high mountains of Mexico was completed in March of 2015 and is now giving us a new view of the TeV sky. HAWC is 15 times more sensitive than the previous generation of widefield EAS gamma-ray instruments and is able to detect the Crab nebula at >6σ with each daily transit. In our first year of operation, HAWC has a 5σ detection sensitivity for a source of ~50mCrab. Unlike Imaging Atmospheric Cherenkov Telescopes (IACTs), HAWC operates 24hrs/day with over a 95% on-time and observes the entire overhead sky (~2sr). HAWC’s peak energy sensitivity is 2-10 TeV which is ~10x higher than IACTs such as VERITAS and HESS, which makes their observations quite complementary. This talk will present results from the first year of HAWC data including our study of the galactic plane including new sources not yet detected by IACTs as well as spectra and morphology of bright sources. In addition, results of our monitoring of transient AGN will be presented.

 
FRIDAY NOON SEMINARS
KICP Friday noon seminar: Unless otherwise noted, all talks are held in ERC 401 at Noon on Fridays.

  • April 1, 2016 | 12:00 PM | ERC 401
    Gravity at the horizon: from the cosmic dawn to ultra-large scales
    Miguel Zumalacarregui, Nordic Institute for Theoretical Physics

    PDF
    Recent advances in cosmology provide both the motivation and the data to probe gravity on the largest scales available to observation. I will revise the landscape of gravitational theories, focusing on modern scalar-tensor theories and their cosmological implications. Then I will present the ongoing effort to test gravity in novel regimes such as the early universe, non-linear effects and ultra-large scales. I will also introduce the hi_class code (www.hiclass-code.net), which is central to this program.
  • April 8, 2016 | 12:00 PM | ERC 401
    High-Scale Axions without Isocurvature from Inflationary Dynamics
    John M Kearney, Fermi National Accelerator Laboratory

    If the PQ-breaking scale f is larger than the inflationary Hubble scale HI, the PQ symmetry is broken during inflation. In the most straightforward models, this gives rise to a light axion field during inflation, which acquires isocurvature fluctuations. Such fluctuations are very stringently constrained by current CMB measurements---in fact, supposing the near-future observation of primordial tensor modes (i.e., a measurement of a non-zero scalar-to-tensor ratio r, indicating a high inflationary scale), these constraints would exclude simple models of QCD axion dark matter in which f is larger than HI. This is particularly problematic for the near-Planckian values of f favored by, for instance, string theory. A variety of solutions have been proposed to ''resurrect'' high-scale axions. Many seek to leverage inflationary dynamics to modify the behavior or potential of the PQ field during inflation in order to suppress isocurvature. However, inflation and the axion potential are both very fragile, and readily disrupted by additional interactions or couplings. As such, it is important to carefully consider the viability of influencing the PQ field via inflationary dynamics; in other words, can this really be accomplished without messing up either inflation or the solution to the strong CP problem? In this talk, I'll discuss the variety of issues that can arise in these constructions, and highlight the steps one must take to build a viable model.
  • April 15, 2016 | 12:00 PM | ERC 401
    A New Measurement of the Hubble Constant
    Dan Scolnic, The University of Chicago

    I will present a new, local, measurement by the SHOES team of the current rate of expansion (H0) of the universe from HST observations of Cepheid variables in host galaxies of Type Ia Supernovae. This measurement is a significant improvement from past measurements, and reduces many systematic uncertainties in past analyses. I will discuss the level of consistency of local measurements with measurements of H0 from the CMB.
  • April 22, 2016 | 12:00 PM | ERC 401
    More Is Different: The Power of Multi-Probe CMB/LSS Cross-Correlations
    Colin Hill, Columbia University

    Overlapping multi-wavelength surveys allow qualitatively new cosmological constraints. In this talk, I will describe three recent such results. (1) I will present a measurement of the kinematic Sunyaev-Zel’dovich (SZ) effect with Planck, WMAP, and WISE data using a novel estimator that does not require redshift estimates for individual tracers. This measurement yields the tightest kinematic SZ-derived constraint on the low-redshift baryon fraction to date, and the result is consistent with the expectation from analyses of the primordial CMB and Big Bang nucleosynthesis. (2) I will describe an updated measurement of the thermal SZ - CMB lensing cross-correlation using the 2015 Planck full mission data. This signal constrains the mass dependence of the "hydrostatic mass bias" afflicting X-ray-based galaxy cluster mass estimates, a key systematic in cluster-based cosmological constraints. (3) I will discuss a constraint on the multiplicative shear bias in CFHTLenS data based on cross-correlations with Planck CMB lensing and CFHTLenS galaxy density maps, the first demonstration of this method on actual data. The result is consistent with a value of the shear bias that would alleviate the tension between cosmological constraints from CFHTLenS and the Planck CMB temperature power spectrum.
  • May 6, 2016 | 12:00 PM | ERC 401
    ETHOS – From Dark Particle Physics to the Matter Distribution of the Universe and Beyond
    Francis-Yan Cyr-Racine, Harvard University

    We formulate an effective theory of structure formation (ETHOS) that enables cosmological structure formation to be computed in a vast array of microphysical model of dark matter physics. This framework maps the detailed microphysical theories of particle dark matter interactions into the physical effective parameters that shape the linear matter power spectrum and the self-interaction transfer cross section of non-relativistic dark matter. These are the input to structure formation simulations, which follow the evolution of the cosmological and galactic dark matter distributions. These effective parameters in ETHOS allow the classification of dark matter theories according to their structure formation properties rather than their intrinsic particle properties, paving the way for future simulations to span the space of viable dark matter physics relevant for structure formation.
  • May 13, 2016 | 12:00 PM | ERC 401
    Resolving the Isotropic Gamma-Ray Background in the Search for Dark Matter
    Mariangela Lisanti, Princeton University

    The presence of all-sky, diffuse gamma-ray emission has been known for several decades, but its origins remain an open question. While astrophysical sources such as Active Galactic Nuclei and star-forming galaxies almost certainly contribute to this Isotropic Gamma-Ray Background (IGRB), dark-matter annihilation may also leave an imprint. Therefore, resolving the components of the IGRB is an important step in pushing the sensitivity to signals of dark matter annihilation, particularly in the well-motivated parameter regime for Weakly Interacting Massive Particles. In my talk, I will present a new analysis method that takes advantage of photon-count statistics to distinguish astrophysical point sources from a potential dark-matter signal. I will show results obtained by applying this technique to public data from the Fermi Large Area Telescope. Using these data-driven methods, we can resolve the vast majority of the diffuse emission at energies greater than ~5-10 GeV as point sources. I will discuss the possible nature of these sources and the implications for dark matter.
  • May 20, 2016 | 12:00 PM | ERC 401
    CMB Lensing Measurements, Present and Future
    Blake D Sherwin, University of California, Berkeley
  • June 3, 2016 | 12:00 PM | ERC 401
    Higgs Relaxation Leptogenesis
    Lauren M Pearce, University of Minnesota & Valparia

 
SPECIAL SEMINARS


 
OPEN GROUP SEMINARS


 
THURSDAY LUNCH DISCUSSIONS
KICP's Thunch: KICP Cosmology Lunch (Thunch) Weekly on Thursdays, Noon, ERC 401A.

Please join us for an informal lunch discussion, led by KICP fellows, of recent news and papers in cosmology. Topics range from experiment and observations to theory in all areas of KICP science. To submit or view papers for this week's Thunch please visit the Thunch website.


 
ASTRONOMY COLLOQUIA
Colloquia of the Department of Astronomy & Astrophysics: Unless otherwise noted, all talks are held in ERC 161 at 3:30 PM on Wednesdays. A reception will be held in Astro Lounge (ERC 501) following the talk.

  • April 6, 2016 | 3:30 PM | ERC 161
    Global Radiation MHD Simulations of Black Hole Accretion Disks
    James Stone, Princeton University

    The inner regions of accretion flows in luminous sources such as AGN and X-ray binaries are radiation dominated. In the case of AGN, radiation and winds produced by such flows are thought to be an important feedback mechanism during galaxy formation in massive halos. I present new results from numerical studies of the magnetohydrodynamics of accretion this regime. These calculations use numerical methods based on a formal solution of the time-dependent radiation transfer equation, eliminating the need for approximate closures. We find that turbulent transport of radiation energy can be a significant contribution to the cooling rate in the disk, and this changes the global properties of the flow compared to standard slim-disk models. We describe new work to extend our calculations to full general relativity, in order to follow the dynamics in the innermost regions of the disk.
  • April 20, 2016 | 3:30 PM | ERC 161
    The Dynamic Last Years in the Lives of Massive Stars
    Eliot Quataert, UC Berkeley

    In the last few years of the lives of massive stars, fusion in the core of the star produces a nuclear power that greatly exceeds the Eddington luminosity. This drives vigorous convection in numerous core and shell burning phases. I describe the surprising effect that waves excited by such convection can have on the properties of massive stars in the years leading up to core collapse. Wave transport of energy into the stellar envelope can power prodigious mass loss in the last years of stellar evolution. Angular momentum transport by waves excited during shell burning phases may well determine the angular momentum of the pre-supernova core, setting the birth spins of compact objects.
  • May 4, 2016 | 3:30 PM | ERC 161
    A data-driven model of stars
    David W Hogg, New York University
    Note: Refreshments served at 4:30 PM, Astro Lounge

    There is a lot of knowledge built in to our physical models of stars. But there is even more information in the sum total of all the data ever taken of stars (tens of thousands of pixels of spectral data on many hundreds of thousands of targets). The Cannon (named after Annie) uses a small amount of physical modeling and a huge amount of data to build very precise, predictive, probabilistic models of stellar spectra. I show that these data-driven models can be used to obtain extremely precise measurements of stellar parameters and detailed chemical abundances, substantially more precise even than the physical models used to generate "ground truth" inputs. Indeed, we believe that The Cannon working on SDSS-APOGEE data is delivering more precise chemical abundance measurements than any previous method for the analysis of stellar spectra. These results have implications for studies of exoplanets (which I won't discuss) and the Milky Way (which I might). Work in collaboration with Melissa Ness (MPIA), Andrew R. Casey (Cambridge), Anna Y. Q. Ho (Caltech) and Hans-Walter Rix (MPIA).
  • May 18, 2016 | 3:30 PM | ERC 401 (Note new location)
    TBA
    Tiziana Di Matteo, Carnegie Mellon University
    Note: Refreshments served at 4:30 PM, Astro Lounge
  • May 25, 2016 | 3:30 PM | ERC 161
    A single prolific r-process event preserved in an ultra-faint dwarf galaxy
    Anna Frebel, MIT, Kavli Institute for Astrophysics and Space Research
    Note: Refreshments served at 4:30 PM, Astro Lounge

    The heaviest elements in the periodic table are synthesized through the r-process, but the astrophysical site for r-process nucleosynthesis is still unknown. The major current candidates are ordinary core-collapse supernovae and neutron star merger. Ancient, metal-poor ultra-faint dwarf galaxies contain a simple fossil record of early chemical enrichment that provides the means to study clean signatures of nucleosynthesis events, and thus, can yield unique information on the origin of these processes. Previously, extremely low levels of neutron-capture elements were found in the metal-poor stars in ultra-faint dwarf galaxies which supported supernovae as the r-process site. Based on Magellan/MIKE high-resolution spectroscopy, we have determined chemical abundances of nine stars in the recently discovered ultra-faint dwarf Reticulum II. Seven stars display extremely enhanced r-process abundances, comparable only to the most extreme r-process enhanced metal-poor stars found in the Milky Way's halo. The enhancement is also 2-3 orders of magnitude higher than that of stars in any of the other ultra-faint dwarfs. This implies the neutron-capture r-process material in Reticulum II was synthesized in a single prolific event that is incompatible with r-process yields from ordinary core-collapse supernovae but consistent with that of a neutron star merger. This would be the first signature of a neutron star merger in the early universe which holds the key to finally identifying the r-process production site. Furthermore, such a single r-process event is a uniquely stringent constraint on the metal mixing and star formation history of this ultra-faint dwarf galaxy. (Alex Ji, Anna Frebel, Ani Chiti, Joshua Simon, 2016, Nature 531, 610, http://arxiv.org/abs/1512.01558)

 
ASTRONOMY TUESDAY SEMINARS

  • April 5, 2016 | 12:00 PM | ERC 576
    Modeling Galaxies in the Era of Precision Cosmology: A community-driven approach with Halotools
    Andrew Hearin, Yale University

    Models of the galaxy-halo connection provide insight into galaxy formation physics and can be exploited to tightly constrain cosmology with observations of large-scale structure. However, theoretical predictions of conventional formulations of these models are plagued by persistent systematic errors, for example due to uncertainty associated with "assembly bias". As galaxy surveys continue to provide ever more precise information on large-scale structure measurements, these theory-level systematics will place a ceiling on the reliability of the conclusions that can be drawn from traditional galaxy-halo techniques. In this talk, I'll describe how the open source Halotools package provides an object-oriented python framework designed to help remedy assembly bias and other systematics associated with nonlinearities in structure formation. Halotools is analogous to Boltzmann codes such as CMBFAST, CAMB and CLASS, but instead provides an optimized pipeline for populating mock galaxy catalogs into both low- and high-resolution simulations. I will conclude by describing how Halotools can be used to provide robust constraints on galaxy formation and help prepare the field of cosmology for the arrival of Stage IV dark energy experiments. Following the talk there will be a tutorial on the Halotools package.
  • May 3, 2016 | 12:00 PM | ERC 161
    Fire and Ice: The role of energetic processes in the cold chemistry of planet-forming circumstellar disks
    Ilse Cleeves, Harvard CfA

    Planets form from the coldest, T<200 K, and densest parts of circumstellar disks around young stars. During this phase, the active nature of the star subjects the disk to relatively high fluxes of UV and X-ray photons and energetic particles. Simultaneously, the local star-forming environment may provide additional external UV and/or radioactive pollutants from recent massive stellar populations. These energetic agents play a vital role in 1) setting protoplanetary disks' turbulent and thermal physics, and 2) regulating the important gas and grain surface chemical reactions, impacting the overall disk molecular composition. Consequently, chemistry can be used to "map out" the important ionizing processes in disks using submillimeter molecular emission. Using data from the Submillimeter Array and Atacama Large Millimeter/Submillimeter Array, we have put strong constraints on the global ionization levels in the disk of TW Hya, constraining the cosmic ray rate to a value two orders of magnitude below the dense interstellar value. This result has major consequences for the active disk chemistry and, in particular, the chemistry of water and organic material. Finally, I will discuss future directions aiming to spatially resolve ionization structure with ALMA and its time variability.
  • May 24, 2016 | 12:00 PM | ERC 576
    TBA
    Jonathan Stern, Max Planck Institute for Astronomy (Heidelberg, Germany)
    Note: Refreshments served at 4:30 PM, Astro Lounge

 
ASTRONOMY SPECIAL SEMINARS

  • May 19, 2016 | 2:00 PM | ERC 401
    TBA
    Joan Schmelz, Arecibo Observatory; Universities Space Research Association