Seminar archive 2015

Raw date Event date Title Speakers Host Summary Links
20150105 Jan. 5, 2015, 2:00 pm Measuring ultra-large cosmological scales with radio telescopes Surveys of large-scale structure using the next generation of radio telescopes will be capable of probing unprecedentedly large volumes of the Universe. This will make it possible to detect effects that occur on length scales on the order of the cosmological horizon size, including primordial non-Gaussianity, general relativistic corrections, and possible signatures of modified gravity.... More »
20150112 Jan. 12, 2015, 2:00 pm Formulation of the First Galaxies under Stellar Feedback The first galaxies, which formed a few hundred million years after the big bang, are related to important cosmological questions. Given that they are thought to be the basic building blocks of large galaxies seen today, understanding their formation and properties is essential to studying galaxy formation as a whole. In this talk, I will... More »
20150120 Jan. 20, 2015, 2:00 pm Towards precision cosmology: the halo model and necessary modifications There are several approaches to account for clustering of matter and its evolution in the Universe. One of the more successful frameworks is the halo model. In this approach, all the matter in the Universe is assumed to be in isolated haloes with mass defined by a threshold density. Despite its success over a decade... More »
20150202 Feb. 2, 2015, 2:00 pm Status of DAMIC at SNOLAB I will present the recent progress achieved by the DAMIC Collaboration in the installation of charge-coupled devices (CCDs) as dark matter detectors in the low background environment of SNOLAB. I will give an overview of the CCD performance, in particular the continuous, low noise (7 eV RMS) operation of the devices under the conditions for... More »
20150209 Feb. 9, 2015, 2:00 pm Baryon Acoustic Oscillations and Redshift Space Distortions The talk will present results about measuring the Baryon Acoustic Oscillation signal in redshift surveys. The impacts of various effects like survey geometries, redshift space distortions, and nonlinear corrections will be discussed. In particular, we will show that redshift-space distortions can substantially sharpen the BAO peak in directions close to the line of sight. We... More »
20150216 Feb. 16, 2015, 2:00 pm Building tomorrow's submm-wavelength instruments with kinetic inductance detectors and on-chip band-defining circuits Recent advances in detector technology have enabled precision studies of the Cosmic Microwave Background and of the dusty high-redshift galaxies that played host to the first generations of star formation. However, there remain significant scientific questions which can only be addressed with massive 100-kilopixel scale cameras, wide-band multichroaic pixels, and compact multi-object spectrometers. I’ll discuss... More »
20150223 Feb. 23, 2015, 12:30 pm Probing the Ultra-High Energy Universe with the Greenland Neutrino Observatory Ultra-high energy neutrino astronomy sits at the boundary between particle physics and astrophysics. Through neutrino astrophysics, we can probe the nature of the ultra-high energy universe in a unique way and test our understanding of particle physics at energies much greater than those achievable at particle colliders. The best limit to date on the flux... More »
20150302 March 2, 2015, 2:00 pm Modeling the Evolution of Galaxy Properties with the Illustris Simulation Cosmological simulations are among the most powerful tools available to probe the non-linear regime of cosmic structure formation. They also provide one of the most powerful testbeds for understanding the impact that hydrodynamics and feedback processes have on the evolution of galaxies. In my talk, I will present galaxy formation simulations that couple a novel... More »
20150309 March 9, 2015, 2:00 pm GRBs, LIGO, and multi-messenger astronomy LIGO should be on the verge of directly detecting gravitational waves. The most likely sources are the inspirals and mergers of stellar mass binary systems, such as pairs of neutron stars and/or black holes. In addition to being extraordinarily loud in gravitational waves, these coalescences may be associated with short gamma-ray bursts, and thus hold... More »
20150310 March 10, 2015, 2:00 pm Impacts of Galaxy Formation and Alternative Dark Matter Models on Milky Way Satellite Kinematics We apply the Jeans equation to identify subhalos in high-resolution numerical simulations that are potentially consistent with observed properties of Milky Way dwarf spheroidal (dSph) galaxies. We investigate the effects found by several recent studies that show changes to the dynamical properties of galactic substructure: the properties of dark matter (DM), and galaxy formation physics.... More »
20150317 March 17, 2015, 2:00 pm Baryon Acoustic Oscillations: A Robust and Precise Route to the Cosmological Distance Scale I will discuss how the acoustic oscillations that propagate in the photon-baryon fluid during the first million years of the Universe provide a robust method for measuring the cosmological distance scale. The distance that the sound can travel can be computed to high precision and creates a signature in the late-time clustering of matter that... More »
20150323 March 23, 2015, 2:00 pm Testing the accuracy of the Frontier-Fields Observatory of Bologna I will show the preliminary results of the Frontier Fields Lens Modeling Comparison Project. The Frontier Field Initiative is currently a major effort of the HST to provide ultra-deep observations of up to six strong lensing clusters. The goal of this survey is to combine the sensitivity of HST with the magnification power of these... More »
20150330 March 30, 2015, 2:00 pm The Milky Way's stellar and dark mass distributions Observations of the structure and dynamics of different stellar populations in the Milky Way’s disk provide a unique perspective on disk formation, evolution, and dynamics. I will present recent progress in our knowledge of the chemo-orbital structure of the disk and discuss the implications for our understanding of how the Milky Way formed and evolved... More »
20150331 March 31, 2015, 2:00 pm A search for dark matter annihilation in the newly discovered dwarf galaxy Reticulum 2 I will present results from a search for gamma-ray emission in nine Milky Way satellites recently discovered in the Dark Energy Survey. The nearest of these, Reticulum 2, shows evidence for a signal in public Fermi data. The detected emission is consistent with annihilating dark matter with a particle mass less than a few hundred... More »
20150406 April 6, 2015, 2:00 pm Status of the DarkSide experiment DarkSide-50 is a direct-detection dark matter experiment operating at the Gran Sasso National Laboratory, searching for nuclear recoils possibly induced by Weakly Interacting Massive Particles (WIMPs). The detector is a 50 kg liquid argon Time Projection Chamber (TPC) that is surrounded by an organic liquid scintillator neutron veto and a water Cherenkov cosmogenic veto. I... More »
20150420 April 20, 2015, 2:00 pm Enabling Dark Energy Survey Science with redMaPPer and redMaGic The Dark Energy Survey is currently taking data, and is poised to be the leading Dark Energy experiment of the second half of this decade. I will present the redMaPPer and redMaGic algorithms, designed to photometrically select clusters and luminous red galaxies respectively, discussing their performance, and how they will enable cluster abundance and baryon... More »
20150427 April 27, 2015, 2:00 pm The Evolution of Quasars with Cosmic Time While the luminosity and mass distributions of quasars has evolved dramatically with cosmic time, the physical properties of quasars of a given luminosity are remarkably independent of redshift. I will describe recent results on the spectra of luminous quasars, the dark matter halos in which they sit, and the intergalactic medium of their host galaxies,... More »
20150506 May 6, 2015, 2:00 pm Probing New Physics Beyond the Standard Model with Cosmology Cosmological observations have provided us with answers to age-old questions, involving the age, geometry, and composition of the universe. However, there are profound questions that still remain unanswered. In this talk, I will describe ongoing efforts to shed light on some of these questions. The origin of the small anisotropies that later grew into the... More »
20150518 May 18, 2015, 2:00 pm Particle Physics at the Yoctowatt Scale: The ADMX-HF Experiment The axion is a hypothetical particle first postulated to explain the absence of CP violation in strong interactions; it is also a well-motivated cold dark matter candidate. Dark matter axions may be detected via their resonant conversion into photons in a high-Q microwave cavity permeated by a strong magnetic field. The Axion Dark Matter eXperiment... More »
20150526 May 26, 2015, 2:00 pm The vicissitudes of the cold dark matter model of cosmology One of the most impressive advances in Physics and Astronomy over the past three decades is the development of the ”standard model of cosmology,” LCDM (where L stands for Einstein’s cosmological constant and CDM for cold dark matter). LCDM accounts for an impressive array of data on the structure of the Universe on large-scale scales,... More »
20150601 June 1, 2015, 2:00 pm The Present and Future of Multi-Object Fiber Spectroscopy The Michigan/Magellan Fiber System (M2FS) has been operational for almost two years and has carried out a wide range of studies from searching for exoplanets, to probing the dark matter content of nearby galaxies, to mapping the distribution of high-redshift galaxies at redshifts of 4-6. I describe some of these results and also discuss how... More »
20150608 June 8, 2015, 2:00 pm SPIDER: exploring the dawn of time from above the clouds TEST Our account of cosmic history begins with inflation, a moment of rapid expansion that set the stage for our universe’s evolution. This inflationary epoch should have left a very faint imprint upon the sky at millimeter wavelengths: a “B-mode” (odd-parity) pattern of polarization in the cosmic microwave background (CMB). January 1st saw the successful... More »
20151109 Nov. 9, 2015, 2:00 pm The Nearby Universe as a Cosmological Lens Over the last decade, large sky surveys have revolutionized our view of the Milky Way and the dwarf galaxies orbiting around it. Much of this observational progress has been motivated by a series of apparent “crises” for the cold dark matter cosmological model. However, these challenges have effectively functioned as flashlights pointing us to interesting... More »
20151116 Nov. 16, 2015, 2:00 pm The Future of Large Mass Calorimeters The detector technology behind SuperCDMS is nearly 20 years old, and thus there is quite reasonable assumption in the scientific community that it is has reached maturity. Alas, this isn’t the case at all! In this talk, I’ll discuss how we hope to improve the energy sensitivity of athermal phonon detectors by 2 orders of... More »
20151123 Nov. 23, 2015, 2:00 pm Darkside-50: Results with UAr DarkSide-50 (DS-50) at Gran Sasso underground laboratory, Italy, is a direct dark matter search experiment based on a Time Projection Chamber (TPC) with liquid argon from underground sources. The DS-50 TPC, with 50 kg of active argon and a fiducial mass of ~37 kg, is installed inside an active neutron veto based on a boron-loaded... More »
20151130 Nov. 30, 2015, 2:00 pm Antimatter Gravity with Muons A longstanding question in physics is whether antimatter falls up. If it does, a simpler cosmology, with no inflation or baryon asymmetry, and no need for dark matter and energy, may be possible. Alternatively, antimatter may fall at nearly the same rate as matter, but violate the equivalence principle slightly, pointing towards a future quantum... More »
20151207 Dec. 7, 2015, 2:00 pm PICO bubble chambers for dark matter The PICO Collaboration, formed from the merger of the Chicago-based COUPP and the Canadian-based PICASSO experiments, uses bubble chambers to search for dark matter. Bubble chambers are a unique dark matter detector technology. They provide very high 10^10 intrinsic electron recoil rejection, the ability to switch nuclear targets, acoustic rejection of alpha events, simple data... More »
20151214 Dec. 14, 2015, 2:00 am Recent Results and Future Prospects in UHECR Observations Ultra-high energy cosmic rays (UHECRs) are the most energetic particles in the universe. Their origins could be related to extremely energetic astronomical phenomena or other exotic processes, such as the decay of the super-heavy dark matter in the halo of our galaxy or topological defects created in an early phase of the development of the... More »