Seminar archive

Raw date Event date Title Speakers Host Summary Links
20130916 Sept. 16, 2013, 2:30 pm CDMSlite: A Search for Light WIMPs The CDMS-low-ionization-threshold-experiment was designed to measure low-energy recoils from Weakly Interacting Massive Particles of mass < 10 GeV. This experiment uses voltage-assisted Luke-Neganov amplification of the ionization-energy deposited by particle interactions, which allows us to probe for light WIMP scatters. In this talk I will describe the physics behind CDMSlite and present science results from... More »
20130923 Sept. 23, 2013, 2:30 pm Searching for Satellite Galaxies of the Milky Way in the Dark Energy Survey During the past decade, wide-field optical surveys have brought to light a population of low-luminosity and highly dark-matter-dominated galaxies in the Local Group, which were discovered by their individually resolved stars. These systems have provided new targets to explore the processes which suppress star formation in low-mass dark matter halos, and to constrain the nature... More »
20130930 Sept. 30, 2013, 2:30 pm Dark matter and flavor I will discuss aspects of dark matter that dominantly couples to third generation quarks, including LHC signatures. I will also discuss one realization of a model of “top-flavored” dark matter that arises from supersymmetry with minimal flavor violation. Notes: 1405
20131002 Oct. 2, 2013, 2:30 pm Fermi Bubbles under Dark Matter Scrutiny The quest for Dark Matter signals in the gamma-ray sky is one of the most intriguing and exciting challenges in astrophysics. In this talk I will use Fermi Bubble photon spectrum to study the signal of Dark Matter. By exploring various setups for the full-sky analysis we achieve stable residual gamma ray spectrum, which can... More »
20131007 Oct. 7, 2013, 2:30 pm Applied Astronomy: Optical Studies of Space Debris at Geosynchronous Orbit The majority of artificial objects in Earth orbit are non-functional: inactive satellites, spent rocket boosters, and parts of spacecraft resulting from collisions and fragmentation events. This population of orbital debris is increasing with time, and represents a collision risk to active spacecraft. Studying the debris population at geosynchronous orbit (GEO, period = 23h56m) is a... More »
20131014 Oct. 14, 2013, 2:30 pm Constraining Dark Matter Models using Fermi-LAT Gamma Ray Observations of the Galactic Center Using Fermi Large Area Telescope (LAT) gamma ray observations, several independent groups have found excess extended gamma ray emission at the Galactic Center. It has been hypothesized that the excess emission may be due to dark matter. However, there are significant uncertainties in the diffuse Galactic background. We reevaluated the data accounting for the spectral... More »
20131021 Oct. 21, 2013, 2:30 pm Interferometers for Cosmic Microwave Background Polarization Measurements Measurement of B-type cosmic microwave background (CMB) polarization is a major goal in cosmology. Its achievement will require instruments with unprecedented control of systematic errors. I will discuss the development of QUBIC, a CMB polarization experiment combining aspects of classical imaging instruments and interferometers, which is currently under development. I will also present results of... More »
20131028 Oct. 28, 2013, 2:30 pm The Evolution of Galaxy Clustering as a Function of Luminosity and Color I present measurements of the luminosity and color-dependence of galaxy clustering over the past eight billion years in the PRIsm MUlti-object Survey (PRIMUS). I quantify how the scale-dependent clustering amplitude increases with increasing luminosity and redder color, with relatively small errors over large volumes (9 sq. deg. of sky). I find that red galaxies have... More »
20131104 Nov. 4, 2013, 2:30 pm Dark Matter in a Hidden Sector A new force connecting the standard model with a hidden sector can arise naturally in various theories of physics beyond the standard model. In particular, light extra U(1) gauge bosons, so called hidden photons, are a theoretically well motivated candidate and could act as mediator of the interaction with dark matter particles in the hidden... More »
20131111 Nov. 11, 2013, 2:00 pm Cosmic Sound, Near and Far The coupling of baryons and photons by Thomson scattering in the early universe leads to a rich structure in the power spectra of the cosmic microwave background photons and the matter. The study of the former has revolutionized cosmology and allowed precise measurement of a host of important cosmological parameters. The study of the latter... More »
20131118 Nov. 18, 2013, 2:30 pm The South Pole Telescope and the Millimeter Sky The South Pole Telescope along with, the Herschel Space Observatory, and the recently commissioned Atacama Large Millimeter Array (ALMA) have opened a window to the millimeter (mm) sky and revealed a unique and unprecedented view of the Universe. I will present an overview of the rich scientific questions which are currently being addressed by studying... More »
20131121 Nov. 21, 2013, 12:00 pm Inflationary Models after Planck An unprecedented opportunity to constrain the inflationary theory is provided by the current flow of high accuracy astrophysical data, among which are the Cosmic Microwave Background measurements by the Planck satellite. This is however a challenging project given the size of the inflationary landscape which contains hundreds of different scenarios. In this talk I will... More »
20131125 Nov. 25, 2013, 2:30 pm Challenges of Relic Neutrino Detection and the Status of the PTOLEMY Experiment A new experiment called PTOLEMY (Princeton Tritium Observatory for Light, Early-Universe, Massive-Neutrino Yield) is under development at the Princeton Plasma Physics Laboratory with the goal of challenging one of the most fundamental predictions of the Big Bang – the present-day existence of relic neutrinos produced less than one second after the Big Bang. With the... More »
20131202 Dec. 2, 2013, 2:30 pm The Quest for Primordial Non-Gaussianity Vanilla single-field, slow-roll inflationary theory predicts that primordial fluctuations in the universe were nearly Gaussian random, although some very well-motivated models specifically predict observably large non-Gaussianity. Measurements of primordial non-Gaussianity therefore represent a rare window into the physics moments after the Big Bang. I first review the history of measurements of non-Gaussianity from the cosmic... More »
20131209 Dec. 9, 2013, 2:30 pm Re-discovering the Radio Transient Sky The Astronomy & Astrophysics Decadal Survey identified time domain astronomy as one of the emerging frontier areas, potentially leading to transformational discoveries. Observations at radio wavelengths have illustrated the potential of the time domain (or “transients”), most notably with the discovery of neutron stars as radio pulsars, a discovery later awarded a Nobel Prize. Since... More »
20131216 Dec. 16, 2013, 2:30 pm News from the low-mass WIMP front I’ll discuss some recent developments in direct searches for dark matter focusing on low-mass WIMPs, including LUX, CoGeNT and COUPP/PICO. Notes: 1357
20140122 Jan. 22, 2014, 3:00 pm Weak Lensing Magnification and Large Scale Structure Gravitational lensing, the deflection of photons by changes in gravitational potential, modifies the observed brightness and shape of galaxies that lie behind massive objects. In an astronomical survey, the detected number count density of sources and their apparent brightnesses will be modified by the magnification effects of gravitational lensing. By measuring these effects we can... More »
20140127 Jan. 27, 2014, 2:30 pm Cosmology Results from the Pan-STARRs Supernova Survey The Pan-STARRs supernova survey has discovered one of the largest samples of Type Ia supernovae. Measurements of the distances to these supernovae allow us to probe some of the most fundamental questions about the properties of the universe like what is dark energy. When combining measurements from various astrophysical probes, we find interesting tension with... More »
20140203 Feb. 3, 2014, 2:30 pm Some New Isocurvature Directions I will discuss two unexplored parts of isocurvature parameter space. In one, the compensated isocurvature mode (a fluctuation in the cosmic baryon fraction), the usual linear theory observables are hidden, and the model unconstrained using familiar analyses. Instead, the hypothesis can be tested using the CMB trispectrum (put alternatively, using off-diagonal correlations). After developing the... More »
20140210 Feb. 10, 2014, 2:30 pm The Fermilab Holometer: A Measurement of Planck Scale Quantum Geometry We are developing an instrument to determine whether a newly predicted position uncertainty is compatible with experiment. The possibility that information in a system scales as its surface area rather than its volume – the holographic principle – motivates this prediction. The required position uncertainty, scaled by the entropy of black holes, is of a... More »
20140217 Feb. 17, 2014, 2:30 pm Detecting Small Planets orbiting Small Stars Thanks to Kepler, today we know that small stars often host Earth-size planets. Approximately half of all stars are low-mass M dwarfs, and at least half of these may have an Earth-size companion. This means it is likely that there are Earth-like planets within just a few parsecs of the Sun. Given the cool temperature,... More »
20140224 Feb. 24, 2014, 2:00 pm Large-Scale Structure Formation with Massive Neutrinos The lightest known massive particle in the Universe, the neutrino, is the focus of major terrestrial experiments. The physics of the neutrino sector is also being probed by ongoing and upcoming cosmological surveys. First postulated in 1930 by Wolfgang Pauli and discovered in 1956 by Cowan and Reines, the neutrino continues to surprise physicists. Introduced... More »
20140303 March 3, 2014, 2:00 pm The high-energy cosmic-ray sky as seen by IceCube, IceTop and AMANDA Cosmic rays with energies in the TeV-PeV range are believed to originate in astrophysical accelerators within our galaxy. During their propagation, cosmic rays are scattered by the Galactic magnetic field, a process that makes their arrival directions at Earth almost entirely isotropic. However, anisotropy with per-mille amplitude, or lower, should subsist in the cosmic-ray sky.... More »
20140310 March 10, 2014, 12:30 pm The Characterization of the Gamma-Ray Signal from the Central Milky Way: A Compelling Case for Annihilating Dark Matter In scenarios where dark matter particles can annihilate to produce standard model, the galactic center of the Milky Way is expected to provide the highest flux from dark matter in the sky. This has allowed galactic center observations to set extremely stringent limits on the parameters of the dark matter particle. Recently, we have worked... More »
20140310 March 10, 2014, 2:00 pm DarkSide-50: Performance and results from the first atmospheric argon run DarkSide-50 is the first physics detector of the DarkSide family, featuring a two-phase underground-argon Time Projection Chamber (50 kg sensitive mass) surrounded by an organic liquid scintillator veto (30 tonnes) and a muon water-Cherenkov detector (1000 tonnes). The two-phase detector is currently operating at Gran Sasso underground laboratory, fully shielded and filled with research grade... More »
20140317 March 17, 2014, 2:00 pm An argument that the dark matter is axions An argument is presented that the dark matter is axions, at least in part. It has three steps. First, axions behave differently from the other forms of cold dark matter because they form a rethermalizing Bose-Einstein condensate (BEC). Second, there is a tool to distinguish axion BEC from the other dark matter candidates on the... More »
20140331 March 31, 2014, 2:00 pm Weak Gravitational Lensing of Galaxy Clusters As the most massive bound objects in the universe, galaxy clusters are excellent probes of the underlying mass density field. The abundance of clusters as a function of mass and their spatial clustering directly constrain the overall mass density of the universe, as well as higher order properties such as the variance in the mass... More »
20140407 April 7, 2014, 12:30 pm Gravitational Wave Detectors in Europe and the US The detection of Gravitational waves is widely viewed as a “new window to the universe”. We report on the current effort of building the second generation of ground-based Gravitational-wave detectors in Europe and the US, as well as some related research. Detectors like Virgo (Italy), LIGO (US), and the smaller GEO600 (Germany) are technically complex,... More »
20140407 April 7, 2014, 2:00 pm Weighing the Giants: Accurate Weak Lensing Mass Measurements for Cosmological Cluster Surveys Surveys of galaxy clusters provide a sensitive probe of cosmology by measuring the evolution of the halo mass function. With a number of surveys at optical, millimeter, and X-ray wavelengths on-going or starting in the near futures, cluster count experiments will be one the most important cosmological probes over the next decade. However, none of... More »
20140421 April 21, 2014, 2:00 pm Big B, Little B, What Begins with B? Bandits, B Modes, and Bispectrumese One of the principal goals of early-Universe cosmology is detection of the characteristic curl, or “B mode,” signal in the cosmic microwave background (CMB) polarization. In this talk, I will discuss a new adaptive-survey strategy, inspired by the multi-armed-bandit problem in probability theory, to optimize the sensitivity of experiments to these B modes. I will... More »
20140505 May 5, 2014, 2:00 pm Latest Results from the Cluster Lensing and Supernovae Survey with Hubble (CLASH) The Cluster Lensing And Supernova survey with Hubble (CLASH) combines the gravitational lensing power of 25 massive clusters with the panchromatic imaging power of HST. It’s four primary scientific objectives are 1) map, with unprecedented accuracy, the distribution of dark matter in galaxy clusters and place constraints on the nature of the dark matter, 2)... More »
20140507 May 7, 2014, 3:00 pm Projects to search WIMPS and neutrinoless double beta decays at the Center for Underground Physics The Dark Energy Survey (DES) is an ongoing Stage III cosmology survey in optical to near-infrared wavelengths. I will briefly review the current state of the survey and demonstrate how ongoing improvements of data quality and consistency have enabled the first publication based on DES data, a lensing analysis of four massive galaxy clusters. I... More »
20140512 May 12, 2014, 2:00 pm Searching for Axions The axion is a hypothetical elementary particle whose existence would explain the baffling absence of CP violation in the strong interactions. Axions also happen to be a good dark-matter candidate. Even if dark-matter axions comprised the overwhelming majority of mass in the universe, they would be extraordinarily difficult to detect. However, several experiments are either... More »
20140602 June 2, 2014, 2:00 pm Introducing Clustering Redshifts I will present a new method to infer the redshift distribution of astronomical datasets. The technique, based on spatial correlations, can be applied to any photometric sample, discrete or continuous, and at any wavelength. I will present a number of results using datasets in the UV, optical, IR and radio wavelengths. Notes: 1304
20140609 June 9, 2014, 2:00 pm SPIDER: A Balloon-Borne Polarimeter for Cosmic Microwave Background Observation SPIDER is a balloon-borne polarimeter designed to characterize the primordial gravitational wave signal in the degree-scale B-mode polarization of the cosmic microwave background (CMB). With six independent telescopes housing a total of 2000 detectors in the 90 GHz and 150 GHz frequency bands, SPIDER is poised to be the most sensitive CMB polarimeter on the... More »
20140616 June 16, 2014, 2:00 pm A WISE search for large extraterrestrial civilizations: a complementary approach to traditional SETI If alien civilizations exist throughout the universe, many have had billions of years to develop technology, expand their population and energy supplies, and travel across their galaxies. Kardashev classified hypothetical advanced civilizations by the magnitude of their power supply, with Type II civilizations harnessing most of the energy output of their host star, and Type... More »
20140617 June 17, 2014, 2:00 pm Digital Readout for UV through Near-IR MKIDs ARCONS, the ARray Camera for Optical to Near-IR Spectrophotometry, is a photon counting integral field unit optimized to observe 400-1100 nm. It is built around a 2024 pixel array of MKIDs (Microwave Kinetic Inductance Detectors), an emerging superconducting detector technology. MKIDs are frequency domain multiplexed and are read out over two feedlines, using tones at... More »
20140623 June 23, 2014, 2:00 pm Evidence for High Energy Astrophysical Muon Neutrinos with IceCube One of the long-standing goals of high energy neutrino astronomy has been to observe muons produced by muon neutrinos which, due to their ability to point back along their direction of travel, can pave the way to locating astrophysical sources of neutrinos and cosmic rays. In this talk I will show preliminary results from a... More »
20140730 July 30, 2014, 10:30 am The Growth of Supermassive Black Holes with their Co-Evolution with Galaxies Using multi-wavelength surveys like GOODS, COSMOS, and Stripe 82X, we measure the growth of supermassive black holes at the centers of galaxies over the last 10 billion years. Most actively growing black holes are heavily obscured and thus are not seen in large area optical surveys like the Sloan Digital Sky Survey; furthermore, obscuration is... More »
20140806 Aug. 6, 2014, 2:30 pm Understanding Cosmic Acceleration with DES and Beyond The Dark Energy Survey (DES) is a large imaging sky survey designed to enable us to understand the physics underlying the accelerated expansion of the Universe. Cosmic acceleration can be explained either by invoking a new energy component to the Universe, dark energy, or by introducing a new fundamental theory of gravity. In either case... More »
20140812 Aug. 12, 2014, 11:00 am Facing the challenge: Gravitational lensing in DES The Dark Energy Survey (DES) is an ongoing Stage III cosmology survey in optical to near-infrared wavelengths. I will briefly review the current state of the survey and demonstrate how ongoing improvements of data quality and consistency have enabled the first publication based on DES data, a lensing analysis of four massive galaxy clusters. I... More »
20140908 Sept. 8, 2014, 11:00 am Time Delay Cosmology Thousands of strong gravitational lenses will be found by time domain surveys such as DES and LSST. Time delays between multiple images can be used to form a geometric time delay distance, a cosmological probe with some unique sensitivities and complementarities. In addition to the cosmology impact, I discuss the statistics challenge of accurate estimation... More »
20140915 Sept. 15, 2014, 2:00 pm New Physics and Indirect Dark Matter Detection Can we learn about New Physics with astronomical and astro-particle data? Understanding how this is possible is key to unraveling one of the most pressing mysteries at the interface of cosmology and particle physics: the fundamental nature of dark matter. I will discuss some of the recent puzzling findings in astro-particle and astronomical observations that... More »
20140922 Sept. 22, 2014, 2:00 pm Testing Neutrino Properties with Large-scale Structure The large-scale structure of our universe (the distribution of galaxies on very large-scales for instance) contains a wealth of information about the origin, evolution, and matter content of the universe. I will discuss physical effects of the cosmic neutrino background on the process of structure formation and present new signatures of massive cosmic background neutrinos... More »
20140929 Sept. 29, 2014, 2:00 pm The Ice Cube Puzzle Astrophysical neutrinos are unambiguous tracers of hadronic interactions of cosmic rays (CRs) in our Universe. With this in mind, high energy neutrino astronomy has long been anticipated to help uncover the origin of high energy CRs. The recent detection of a flux of high-energy extraterrestrial neutrinos by the IceCube Observatory is an important step in... More »
20141006 Oct. 6, 2014, 2:00 pm Implications of the Candidate Dark Matter Decay Line at 3.5 keV Two independent groups have detected an unidentified X-ray line at 3.5 keV that is consistent with the dark matter density in the field of view of the observations toward the Perseus Cluster, stacked X-ray clusters, Andromeda, and the Milky Way Galactic Center. I will discuss the sterile neutrino dark matter decay interpretation of the line,... More »
20141013 Oct. 13, 2014, 2:00 pm Lyman alpha Forest in optically thin cosmological simulations The Lyman-alpha forest is the main tracer of cosmological structure at high redshifts, 2<z<4, accessible to current (BOSS/eBOSS) and future (DESI) sky surveys. On large-scales, the Ly-a power spectrum is used as a standard ruler, measuring the Baryon acoustic oscillations (BAO) scale at high redshifts. On small-scales, the Ly-a forest allows one to constrain neutrino... More »
20141020 Oct. 20, 2014, 2:00 pm Cosmic Reionization on Computers I will review the field of numerical simulations of cosmic reionization: the process of ionizing of intergalactic medium by high redshift galaxies and quasars. I will describe the main physical processes that are important for modeling reionization, explain how these processes are incorporated in computer simulations, and will use simulations to gain insight into the... More »
20141027 Oct. 27, 2014, 2:00 pm Cosmic ray anisotropies and nearby sources Recently, the AMS-02 collaboration has presented data on cosmic ray protons, Helium, electrons and positrons as well as the boron-to-carbon ratio. We present the first consistent modeling of these data, paying particular attention to the contribution due to production and acceleration of secondary electrons and positrons in nearby supernova remnants. This process results in an... More »
20141103 Nov. 3, 2014, 2:00 pm Cosmic Reionization Cosmic reionization, and the preceding ‘dark ages’, corresponds to the epoch when light from the first galaxies reionized the neutral intergalactic medium (IGM) that pervaded the Universe following recombination. This epoch is the last frontier in the study of cosmic evolution, corresponding to the formation of the first galaxies and black holes. I will discuss... More »
20141110 Nov. 10, 2014, 2:00 pm The non-universality of halo density profiles The density profiles of dark matter halos are an essential input for models of galaxy formation, as well as for the interpretation of numerous observations such as weak and strong lensing signals. The profiles are commonly thought to follow a simple, universal shape, and only depend on two parameters, mass and concentration. Using a large... More »
20141114 Nov. 14, 2014, 10:00 am The axion search plan at the Center for Axion and Precision Physics in Korea The center for axion and precision physics research (CAPP) in Korea is recently been established by the Institute for Basic Science (IBS) of South Korea to establish a state of the art axion dark matter experiment in Korea and play a leadership role in the storage ring proton EDM experiment. With a number of new... More »
20141117 Nov. 17, 2014, 2:00 pm Probing Dark Energy with the Canadian Hydrogen Intensity Mapping Experiment (CHIME) CHIME will use the 21cm emission line of neutral hydrogen to map large-scale structure between redshifts of 0.8 and 2.5. By measuring BAO we will place constraints on the dark energy equation of state as it begins to dominate the expansion of the Universe, particularly at redshifts poorly probed by current BAO surveys. In this... More »
20141120 Nov. 20, 2014, 1:30 pm Dark Matter Complementarity The cosmic reionization, and the preceding ‘dark ages’, corresponds to the epoch when light from the first galaxies reionized the neutral intergalactic medium (IGM) that pervaded the Universe following recombination. This epoch is the last frontier in the study of cosmic evolution, corresponding to the formation of the first galaxies and black holes. I will... More »
20141124 Nov. 24, 2014, 2:00 pm MKIDs at FNAL: From Detector R&D to Dark Energy Science We will discuss the progress done over the last couple of years on R&D for UV-VIS-IR MKIDs. This will include a description of the activities in the lab, and at telescopes. We will also present our plans for a prototype instrument at the 4m telescope at SOAR. Finally, the potential of these sensors as new... More »
20141208 Dec. 8, 2014, 2:00 pm Planck 2014 Cosmology Results The Planck 2014 cosmology likelihood will include the tightest measurements to-date of CMB polarization at intermediate angular scales. I will present parameter constraints on LCDM and extensions from these data, including on the effective number and masses of the neutrinos, as well as other parameters describing dark matter, axions, and inflation. In doing so, I... More »
20141215 Dec. 15, 2014, 2:00 pm The outskirts of Milky-Way mass galaxies - a probe of dark matter driven growth Dark matter is central to our idea of how galaxies grow and develop. Dark matter overdensities trigger the initial collapse, dark matter halos merge and grow continuously to the present day, and dark matter constitutes most of the gravitationally important mass in present-day galaxies. Yet, we know precious little about the actual dark matter merger... More »
20141216 Dec. 16, 2014, 1:00 pm Optical Spectroscopy with Starbugs, from TAIPAN to the Giant Magellan Telescope The majority of astronomical fibre-fed spectroscopic instruments rely on sequential positioning of fibres that require significant time (up to an hour in some cases) to reconfigure a field for observation, thus reducing the amount of on-sky time available for any instrument. Starbugs, a novel fibre-positioning technology developed by the Australian Astronomical Observatory, allow for simultaneous... More »
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 »
20160111 Jan. 11, 2016, 2:00 am Fast Radio Bursts I will report on the discovery of a new fast radio burst with a detection of Faraday rotation, wavelength-dependent scattering, and scintillation. The data imply source location in the dense central region of its host galaxy or the presence of magnetized material associated with the source itself. The burst was detected with GBT at 800MHz.... More »
20160125 Jan. 25, 2016, 2:00 am Advances in millimeter-wavelength instrumentation with the South Pole Telescope The Cosmic Microwave Background (CMB) is a powerful cosmological tool, containing the imprint of signals from both the early and late universe. Over the past few years, CMB experiments made significant technological advances that led to the first detection of the extremely faint B-mode polarization signal. Using this signal, experiments have the potential to constrain... More »
20160201 Feb. 1, 2016, 2:00 pm Quantum Twists of Space The talk will review theoretical arguments that if space and time emerge from a quantum system at the Planck scale, there should be nonlocal exotic quantum correlations of positions of massive bodies, even on scales much larger than the Planck length. In relational theories with no fixed background space, these could take the form of... More »
20160208 Feb. 8, 2016, 2:00 pm Helical Magnetic Fields in the Cosmos It is often necessary to study cosmological phase transitions, such as inflation and thermal symmetry-breaking phenomena, through the relics that they leave behind. In this sense, the cosmological magnetic field may be a powerful probe of the early universe, which has yet to be tapped. In this talk, I will survey various topics related to... More »
20160215 Feb. 15, 2016, 2:00 pm CRESST: A direct search for (light) dark matter particles Today, many observations on various astronomical scales provide compelling evidence for the existence of dark matter. Its underlying nature, however, remains an open question of present-day physics. Direct searches aim to find the answer by observing dark matter particles interacting in their detectors. One of the numerous experiments around the globe is CRESST-II, the only... More »
20160222 Feb. 22, 2016, 2:00 pm Pulsar timing limit on gravitational waves necessitates re-assessment of binary supermassive black hole population Mergers of massive galaxies are thought to form binary supermassive black holes, which coalesce through losses of energy and angular momentum to gravitational radiation. For the last decade, collaborations worldwide have been searching for signatures of these gravitational waves in radio timing measurements of millisecond pulsars. The intended sensitivities of these experiments, based on theoretical predictions,... More »
20160229 Feb. 29, 2016, 2:00 pm Chameleon dark energy If dark energy consists of a light scalar field, it might be detectable as a “fifth force” between ordinary-matter objects, in potential conflict with precision tests of gravity. Chameleon fields and other theories with screening mechanisms, however, can evade these tests by suppressing the forces in regions of high density, such as the laboratory. The... More »
20160307 March 7, 2016, 2:00 pm New Cosmological Results from Type Ia Supernovae Type Ia Supernovae play a critical role in measuring dark energy as well as the Hubble Constant. I will go over the latest results from each of these important measurements. I will also discuss the latest interpretations about possible `tension’ in these measurements from different probes including BAO and CMB. I will show what role... More »
20160314 March 14, 2016, 2:00 pm Always in the Last Place You Look: Three New Directions for Dark Matter Detection Searches for dark matter over the last two decades have mainly focused on the Weak-scale mass range. With no detection yet, either in underground searches or the LHC, our best hope going forward is to expand our search to cover as many types of dark matter as possible. I will discuss three budding direct detection... More »
20160321 March 21, 2016, 2:00 pm Next Generation Cosmological Constraints on the Dark Sector and Gravity A rich portfolio of upcoming complementary cosmological experiments will be producing data in the next 5-10 years. I will discuss the goals of the LSST Dark Energy Science Collaboration and the challenges faced to achieve them. I will also discuss ways in which LSST and the other surveys can be used in conjunction to extract... More »
20160328 March 28, 2016, 2:00 pm TBA
20160328 March 28, 2016, 2:00 pm Joining Forces against the Dark Side of the Universe: From the Cosmic Microwave Background to the Large Scale Structure Despite tremendous recent progress, gaps remain in our knowledge of our understanding of the Universe. We have not yet pinned down the properties of dark energy, nor have we confirmed Einstein’s theory of Gravity at the largest scales. Current and upcoming large sky surveys of the Cosmic Microwave Background (CMB), Large Scale Structure (LSS) in... More »
20160404 April 4, 2016, 2:00 pm From Detector to Observatory On September 14, 2015 LIGO made the first direct detection of gravitational waves, marking the transition of the LIGO instruments from detectors to observatories, and the beginning of the era of gravitational wave astronomy. GW150914 provided the first observational proof that binary black holes not only exist, but that they exist in large numbers and... More »
20160411 April 11, 2016, 2:00 pm Special Colloquium (Title TBD) TBD
20160418 April 18, 2016, 2:00 pm Baryogenesis via Particle-Antiparticle Oscillations CP violation, which is crucial for producing the baryon asymmetry of the Universe, is enhanced in particle-antiparticle oscillations. We study particle-antiparticle oscillations (of a particle with mass O(100 GeV)) with CP violation in the early Universe in the presence of interactions with O(ab-fb) cross-sections. We show that, if baryon-number-violating interactions exist, a baryon asymmetry can... More »
20160425 April 25, 2016, 2:00 pm Stellar-Dynamical Inferences about Dark Matter in the Smallest Galaxies The Local Group’s dwarf galaxies include the nearest, smallest, oldest, darkest and least chemically-enriched galaxies known. I will summarize recent results – and present new ones – regarding the amount and spatial distribution of dark matter within these systems. Implications range from tests of the standard `cold dark matter’ model of cosmological structure formation to... More »
20160502 May 2, 2016, 2:00 pm Cosmological Seed Magnetic Field from Inflation A cosmological magnetic field of nG strength on Mpc length scales could be the seed magnetic field needed to explain observed few microG large-scale galactic magnetic fields. I first briefly review the observational and theoretical motivations for such a seed field, two galactic magnetic field amplification models, and some non-inflationary seed field generation scenarios. I... More »
20160511 May 11, 2016, 2:00 pm Resolving the Isotropic Gamma-Ray Background in the Search for Dark Matter 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... More »
20160511 May 11, 2016, 2:00 pm Resolving the Isotropic Gamma-Ray Background in the Search for Dark Matter 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... More »
20160516 May 16, 2016, 2:00 pm Searching for Dark Matter with Sounding Rockets High-resolution X-ray spectrometers onboard suborbital sounding rockets can search for dark matter candidates that produce X-ray lines, such as decaying keV-scale sterile neutrinos. Even with exposure times and effective areas far smaller than XMM and Chandra observations, high-resolution, wide field-of-view observations with sounding rockets have competitive sensitivity to decaying sterile neutrinos. We analyze a subset... More »
20160523 May 23, 2016, 2:00 pm Simulations of Strong Gravitational Lensing Gravitational lensing is one of the most powerful tools for investigating the dark side of the Universe. Strong gravitational lensing in particular provides a unique probe of the cores of massive dark matter halos. However, understanding this phenomena based upon observational data alone is complicated; high-fidelity simulations are required for robust cosmological interpretations. To fulfill... More »
20160523 May 23, 2016, 2:00 pm Simulations of Strong Gravitational Lensing Gravitational lensing is one of the most powerful tools for investigating the dark side of the Universe. Strong gravitational lensing in particular provides a unique probe of the cores of massive dark matter halos. However, understanding this phenomena based upon observational data alone is complicated; high-fidelity simulations are required for robust cosmological interpretations. To fulfill... More »
20160606 June 6, 2016, 2:00 pm Galaxy Cluster Cosmology with the South Pole Telescope Measurements of the abundance of galaxy clusters are an established cosmological probe and a promising tool for measuring the properties of dark energy and cosmic structure formation. To achieve the required level of accuracy, a clean survey selection and robust mass calibration from various observables is crucial. In this talk, I will review the cluster... More »
20160627 June 27, 2016, 2:00 pm Interpreting Observations of Galaxy Cluster Outskirts A variety of astrophysical processes affect the evolution of the intracluster medium (ICM) and corresponding observational signatures. While gas in the cluster core is most sensitive to cooling and feedback processes, gas in cluster outskirts is most sensitive to physical processes driven by accretion. I will present cosmological simulations of galaxy cluster formation that follow... More »
20160718 July 18, 2016, 2:00 pm Observations and Simulations of Galaxy Clusters: Cluster Radio Galaxies and their Implications on SZE Signal, Simulated Pressure Profiles and SZE Mass-Observable Relation We study the overdensity of point sources in the direction of X-ray-selected galaxy clusters from the Meta-Catalog of X-ray detected Clusters of galaxies (MCXC; ⟨z⟩ = 0.14) at South Pole Telescope (SPT) and Sydney University Molonglo Sky Survey (SUMSS) frequencies. Flux densities at 95, 150 and 220 GHz are extracted from the 2500 deg2 SPT-SZ... More »
20160815 Aug. 15, 2016, 2:00 pm The multiple effects of AGN feedback in galaxy clusters TBA
20160912 Sept. 12, 2016, 2:00 pm Scintillating bubble chambers: Results from a 35-gram prototype xenon bubble chamber In both direct WIMP dark matter search and coherent neutrino-nucleus elastic scattering experiments, discriminating low-energy nuclear recoils from all the other backgrounds is the key to detector performance. The bubble chambers developed by the PICO collaboration for dark matter detection feature both unmatched electron-recoil background rejection and the unique ability to work with a variety... More »
20160919 Sept. 19, 2016, 2:00 pm Neutrino Decay and Non-Unitary Effects in Neutrino Oscillations Discussion on current bounds on the neutrino lifetime, along with a more general parameterization of “general decay” effects in neutrino flavor oscillation.
20160926 Sept. 26, 2016, 2:00 pm Early Reionization Science from 21cm Experiments and the Path Towards a New Cosmological Probe 21 cm cosmology — the concept of using radio telescopes to observe the highly redshifted 21 cm line of neutral hydrogen on cosmological scales — is a field on the verge of a breakthrough.   The first generation of 21 cm cosmology experiments (LOFAR, MWA, and PAPER, among others) have been operating for several years,... More »
20160926 Sept. 26, 2016, 2:00 pm Early Reionization Science from 21cm Experiments and the Path Towards a New Cosmological Probe 21 cm cosmology — the concept of using radio telescopes to observe the highly redshifted 21 cm line of neutral hydrogen on cosmological scales — is a field on the verge of a breakthrough. The first generation of 21 cm cosmology experiments (LOFAR, MWA, and PAPER, among others) have been operating for several years, and... More »
20161010 Oct. 10, 2016, 2:00 pm Searches for New Physics with X-ray data A discussion on searches for new physics using ultra-deep X-ray observations of the central Active Galactic Nucleus of the Perseus galaxy cluster. We find two anomalies at high significance that we are unable to account for through conventional instrumental or astrophysical processes. I will outline interpretations of these anomalies from axion-photon mixing and from a... More »
20161017 Oct. 17, 2016, 2:00 pm Soft Limits, Asymptotic Symmetries and Inflation in Flatland There has been much recent interest in soft limits, both of flat space S-Matrix elements and of cosmological correlation functions. We will discuss the physics probed by soft limits in cosmology and explore the connection between cosmological soft theorems and asymptotic symmetries. These ideas will be illustrated by a simple example: inflation in 2+1 dimensions.
20161031 Oct. 31, 2016, 2:00 pm Recent Results from the PandaX- II experiments The Particle and Astrophysical Xenon (PandaX) project is a series of xenon-based ultra-low background experiments in the China JinPing Underground Laboratory (CJPL) targeting the unknown physics of dark matter and neutrinos. The first and second stage experiments (PandaX-I and II) both utilize dual-phase xenon time projection chamber (TPC) to carry out direct search for the... More »
20161107 Nov. 7, 2016, 2:00 pm Baryon Component Covariance and Stacked Spectroscopic Masses of Galaxy Clusters This talk will cover recent improvements to the characterization of the cosmic population of massive halos. After briefly reviewing an underlying statistical model for multi-property counts and conditional statistics, I will present preliminary observational confirmation of the “closed box” baryonic nature of massive halos predicted by simulations, then follow up with total mass scaling relations... More »
20161114 Nov. 14, 2016, 2:00 pm Recent Results from APTpol:CMB Polarization on Small (and Large) Scales The temperature and polarization of the cosmic microwave background (CMB) have been measured in exquisite detail by space-based probes such as WMAP and Planck over the full sky on large and intermediate scales. However, a healthy community of ground-based and balloon-borne experiments continue probing the CMB at both large and small scales with ever higher... More »
20161121 Nov. 21, 2016, 2:00 pm Accelerating the Search for Dark Matter Axions with Quantum Technology The axion is a hypothetical dark matter particle and many searches rely on its presumed coupling to electromagnetism. Indeed, these experiments amount to looking for an excess of microwave photons in a cryogenic microwave cavity. If all sources of technical noise can be tamed, the sensitivity is ultimately limited by fundamental quantum fluctuations of the... More »
20161128 Nov. 28, 2016, 2:00 pm Search for Dark Matter in Terms of Dark Bound States Understanding the nature of dark matter is an open question of central importance to particle physics and cosmology. In this talk, I discuss a model where the dark matter is a fermion charged under a dark U(1) gauge symmetry and its interactions are mediated by a massive dark photon. I will summarize the current status... More »
20161205 Dec. 5, 2016, 2:00 pm A Monodromy from London A description of large field inflation in terms of a dual massive gauge theory
20161212 Dec. 12, 2016, 2:00 pm New Directions in Dark Matter Detection Observational bounds currently permit the existence of a large number of dark matter candidates, ranging from ultra-light axions with masses ~ 10^(-22) eV to MACHOs with mass as large as 10^(24) gm. It is important to develop experimental methods to constrain this vast range of parameters. In this talk, I will describe new experimental methods... More »
20170123 Jan. 23, 2017, 2:00 pm Coherent Neutrino-Nucleus Scattering: signal of background? The next generation of dark matter direct detection experiments will be sensitive to coherent nuclear scattering of solar neutrinos. This presents an irreducible background to dark matter searches, the so called ‘neutrino floor’. However, this effect that has yet to be observed and so provides an opportunity for discovery. Dedicated experiments are racing to observe... More »
20170130 Jan. 30, 2017, 2:00 pm The ANDES Deep Underground Laboratory in South America: status and prospects The construction of the Agua Negra tunnel through the Andes between Argentina and Chile is a unique opportunity to build a world class deep underground laboratory in the southern hemisphere, with 1750m of rock overburden. At 30 degrees latitude south, far from nuclear power plants, it provides a unique site for Dark Matter searches and... More »
20170206 Feb. 6, 2017, 2:00 pm Discovery of the First Quad(-like) Lensed Quasar System in the Dark Energy Survey Strong gravitational lensing systems provide valuable tools for studying the properties and evolution of galaxies and quasars, for measuring the distribution of dark matter, and for constraining cosmological parameters. In particular, lensed quasar systems, when accompanied by accurate time delay measurements and careful lens modeling, can provide powerful cosmological constraints that are complementary to those... More »
20170213 Feb. 13, 2017, 2:00 pm Canceled
20170220 Feb. 20, 2017, 2:00 pm Cross-Correlating 2D and 3D Galaxy Surveys Galaxy surveys probe both structure formation and the expansion rate, making them promising avenues for understanding the dark universe. Photometric surveys accurately map the 2D distribution of galaxy positions and shapes in a given redshift range, while spectroscopic surveys provide sparser 3D maps of the galaxy distribution. In this talk, I will present a way... More »
20170227 Feb. 27, 2017, 2:00 pm Interplay between dark and baryonic matter in galaxy centers: new constraints from dynamics and lensing The central 5-10 kpc of elliptical galaxies, while in long term steady state, are not truly relaxed. The primary reason is that baryons and dark matter are not fully mixed with each other. We demonstrate this by comparing observed and simulated galaxies to theoretically derived prediction for dynamically relaxed collisionless systems, and by examining the... More »
20170306 March 6, 2017, 2:00 pm Direct Detection of sub-GeV Dark Matter Dark matter with MeV-to-GeV masses is a theoretically and phenomenologically appealing possibility. In this talk, I will describe how direct-detection experiments can probe this under-explored mass range. A demonstrated technique with significant potential for improvement is that dark matter scatters off electrons, causing ionization or excitation of atoms in a detector target material, which can... More »
20170313 March 13, 2017, 2:00 pm Cores in Dwarf Galaxies from Fermi Repulsion James Unwin, UIC Cold dark matter provides a remarkably good description of cosmology and astrophysics. However, observations connected with small scales might be in tension with this framework. In particular, structure formation simulations suggest that the density profiles of dwarf spheroidal galaxies should exhibit cusps, in contrast to observations. I will show that Fermi repulsion can explain the... More »
20170320 March 20, 2017, 2:00 pm Compact dark matter Marc Kamionkowski, Johns Hopkins Considerable attention has focused the past year on the possibility that some or all of the dark matter could be composed of compact dark objects with masses around 30 solar masses.  The hypothesis has led to interesting connections to gravitational-wave astrophysics, fast radio bursts, pulsar timing arrays, galaxy surveys, gravitational lensing, and stellar dynamics.  I... More »
20170327 March 27, 2017, 2:00 pm Weyl Symmetry, Inflation, and Spontaneous Generation of the Planck Mass Christopher Hill, Fermilab Scalar fields can be coupled non-minimally to curvature and satisfy: (i) the theory has no mass input parameters, including M_Planck=0; (ii) the scalars have arbitrary values and gradients, but undergo a general expansion and relaxation to constant values that satisfy a nontrivial elliptical constraint K(phi)=constant; (iii) this constraint breaks scale symmetry spontaneously, and the Planck... More »
20170403 April 3, 2017, 2:00 pm New Insights into the Cosmic-Ray Positron Excess Dan Hooper, Fermilab Recent Measurements of the Gaming and B0656+14 pulsars by the gamma-ray telescope HAWC (along with earlier measurements by Milagro) indicate that these objects generate significant fluxes of very high-energy electrons. From the measured gamma-ray intensity and spectrum of these pulsars, one can calculate and constrain their expected contributions to the local cosmic-ray positron  spectrum. Among... More »
20170410 April 10, 2017, 2:00 pm Extrasolar Planets: Lessons From Kelper Yoram Lithwick, Northwestern University Astronomers have been discovering extrasolar planets at an astonishing pace.  The Kepler space telescope has discovered thousands of planets smaller than Neptune. Many of these planets’ properties were completely unexpected, based on how planets were thought to form. I will describe these surprising properties, and explain how we have inferred the densities and eccentricities of... More »
20170417 April 17, 2017, 2:00 pm The Search for Dark Photons at the SeaQuest E906 Experiment Arun Tadepalli, Rutgers The SeaQuest E906 experiment is a fixed target Drell-Yan experiment which is aimed at studying the anti-quark distributions in the nucleon and nuclei. 120 GeV protons from the Main Injector at Fermilab could also be used to search for massive dark gauge bosons or dark photons that could be generated when a proton beam dump... More »
20170424 April 24, 2017, 2:00 pm Gamma-ray Constraints on Decaying Dark Matter and Implications for IceCube Nicholas Rodd, MIT Utilizing the Fermi measurement of the gamma-ray spectrum toward the inner Galaxy, I will explain how to derive some of the strongest constraints on dark matter lifetimes in the mass range from hundreds of MeV to above an EeV.  The limits derived disfavour a decaying DM interpretation of the astrophysical neutrino flux observed by IceCube,... More »
20170501 May 1, 2017, 2:00 pm Gravitational Lensing of the CMB Gil Holder, UIUC Gravitational lensing of the cosmic microwave background is emerging as a new and powerful cosmological tool. I will discuss recent results from the South Pole Telescope, as well as prospects for cosmological measurements of neutrino masses and detection of gravitational waves from the early universe.
20170508 May 8, 2017, 2:00 pm A Cosmic Census – and the means to do it right Peter Melchior, Princeton Weak gravitational lensing is an important driver of large astronomical surveys. It presents the only way to determine the mass distribution in the universe over a wide range of scales: galaxies, galaxy clusters, voids, and the cosmic web as a whole. I will show the latest results of the Dark Energy Survey for each of... More »
20170515 May 15, 2017, 2:00 pm Particle cosmological exploration for light dark matter Kenji Kadota, Institute for Basic Science, S. Korea A few examples for the light dark matter will be
presented along with their cosmological (e.g. galaxies, supernova) and 
the particle physics (collider, dark matter search) constraints to illustrate the complementarity
between the particle physics and cosmology probes.
20170522 May 22, 2017, 2:00 pm New Physics in Astrophysical Neutrino Flavor Teppei Katori, Queen Mary Neutrino oscillation physics is very successful in the last 20 years. Now, our understanding of the Neutrino Standard Model (nuSM) is very matured, and there are world wide effort to measure last missing pieces of nuSM. On the other hand, neutrino oscillation itself can be a tool to look for new physics beyond the nuSM,... More »
20170530 May 30, 2017, 2:00 pm Twinkling Quasars Lensed by Galaxies Lensing Quasars Paul Schechter, MIT Nobody who has looked carefully at the two broad classes of stellar mass estimates for galaxies will question the need for another method. Quasars that are multiply imaged by galaxies twinkle as a result of micro-lensing by the stars that comprise the galaxies.  We have used this to estimate stellar masses for the lensing galaxies. ... More »
20170605 June 5, 2017, 2:00 pm Looking for the WIMP next door Jessie Shelton, UIUC Dark matter (DM) freezing out in a hidden sector is a simple and compelling scenario for the missing 25% of our universe, which can parametrically explain null results in searches to date.  I will demonstrate that the requirement that the dark sector was once in thermal equilibrium with the SM defines a UV-insensitive cosmological history... More »
20170612 June 12, 2017, 2:00 pm Lines, Excesses, and Dwarfs, Oh My! Dark Matter Searches and the Fermi-LAT sky Regina Caputo, University of Maryland/NASA/GAFC The era of precision cosmology has revealed that ~80% of the total amount of matter in the universe is dark matter. One promising candidate, motivated by both particle physics and astrophysics, is the Weakly Interacting Massive Particle (WIMP). WIMPs are predicted to produce gamma rays via annihilation or decay which are detectable by the Fermi... More »
20170619 June 19, 2017, 2:00 pm LUX Postscripts and an LZ Preface Kim Palladino, UW-Madison Liquid xenon time projection chambers are a technology well suited to WIMP direct dark matter searches. The LUX detector completed operations in 2016, and has set its final spin-independent and spin-dependent limits, as well as a limit on axion-like particles. A second generation experiment, LZ, will occupy the cavern vacated by LUX. But first, we... More »
20170626 June 26, 2017, 2:00 pm A New Look at Dark Matter in the Cores of galaxies Thomas Lacroix, University of Montpellier / CNRS Indirect detection techniques are a very promising avenue to look for dark matter (DM) particles by exploiting astrophysical observations. This is especially interesting when studying the centers of galaxies, where DM over-densities are expected. Moreover, DM particles may be significantly clustered in galactic cores around supermassive black holes, forming density spikes. I will present several... More »
20170705 July 5, 2017, 2:00 pm Squeezed Light for Gravitational Wave Interferometers Lee McCuller, MIT Craig Hogan Gravitational Wave detectors use optical interferometry enhanced with long baseline resonant cavities to achieve the sensitivity required for the recent detections of binary black hole inspirals. Advanced LIGO will soon add squeezed coherent states to enhance sensitivity by quantum mechanics. This talk will detail the detector and why this improvement will initially only improve the... More »
20170710 July 10, 2017, 2:00 pm TBD Annika Peter, Ohio State University
20170717 July 17, 2017, 2:00 pm TBD Mathias Pierre
20170724 July 24, 2017, 2:00 pm AGN Feedback in Massive Galaxies Pawel Biernacki, ETH-Zurich Abstract: Supermassive Black Holes (SMBH) are found in the central region of massive galaxies at all redshift in the form of Active Galactic Nuclei (AGN) and are believed to regulate star formation in massive galaxies. Using improved sink particle algorithm to model SMBH in the RAMSES code we studied effects of coevolution of SMBH and... More »
20170731 July 31, 2017, 2:00 pm No seminar -- DPF meeting
20170807 Aug. 7, 2017, 2:00 pm Galaxy Clusters: A Standard Cannon for Cosmology Chris Miller, University of Michigan Einstein’s theory of general relativity (GR) entwines the dynamics of matter-energy and the universe’s expansion. It is often said: matter-energy tells space-time how to curve and space-time tells matter-energy how to move. In the weak-field limits of GR, Newtonian dynamics allows us to relate the escape speed to the local potential via the Poisson equation.... More »
20170814 Aug. 14, 2017, 2:00 pm What We Can Tell About the Sources of IceCube’s Neutrinos, and What IceCube Can Tell Us About Gamma Ray Bursts Peter Denton, Niels Bohr International Academy IceCube has recently detected high energy astrophysical neutrinos for the first time. While many known astrophysical processes are anticipated to create high energy neutrinos, the origin of the observed neutrinos remains unclear. In this talk I will first present evidence disfavoring the Milky Way as the primary origin of the flux based on anisotropy arguments.... More »
20170821 Aug. 21, 2017, 2:00 pm No seminar -- Solar Eclipse
20170828 Aug. 28, 2017, 2:00 pm Cosmology with Clusters of Galaxies Adam Mantz, Stanford The gas mass fractions and the distribution in mass and redshift of the galaxy cluster population provide powerful probes of cosmology, constraining the cosmic matter density, the amplitude of the matter power spectrum, properties of dark energy, and the mass of neutrinos, among other parameters. Improvements in cluster data on several fronts have yielded significant... More »
20170904 Sept. 4, 2017, 2:00 pm No seminar -- Labor Day
20170911 Sept. 11, 2017, 2:00 pm Resolving the physical scale of star formation in a lensed galaxy at z=2.5 Traci Johnson, University of Michigan Clumpy substructure in galaxies 1<z<3 is prevalent and forms from gravitational instabilities in the disk as cold gas accretes from the intergalactic medium. These clumps are the launching points of outflows from massive stars, and will merge over time to build up the exponential disks of today’s galaxies. Even with HST, the highest spatial resolution... More »
20170918 Sept. 18, 2017, 2:00 pm TBD Marilena Loverde, Stony Brook
20170925 Sept. 25, 2017, 2:00 pm TBD Vadim Semenov, University of Chicago
20171002 Oct. 2, 2017, 2:00 pm TBD Phil Cowperthwaite, Harvard
20171009 Oct. 9, 2017, 2:00 pm TBD Scott Hertel, University of Massachusetts Amherst
20171016 Oct. 16, 2017, 2:00 pm TBD Nick Battaglia, Princeton
20171023 Oct. 23, 2017, 2:30 pm TBD TBD
20171030 Oct. 30, 2017, 2:00 pm TBD TBD
20171106 Nov. 6, 2017, 2:00 pm TBD Liang Dai, Princeton
20171113 Nov. 13, 2017, 2:00 pm TBD Peter Behroozi, University of Arizona
20171120 Nov. 20, 2017, 2:00 pm TBD Robert Lasenby, Perimeter
20171127 Nov. 27, 2017, 2:00 pm TBD TBD
20171204 Dec. 4, 2017, 2:00 pm TBD TBD
20171211 Dec. 11, 2017, 2:00 pm TBD Doug Finkbeiner, Harvard
20171218 Dec. 18, 2017, 2:00 pm TBD TBD
20180226 Feb. 26, 2018, 2:00 pm Stellar Streams Discovered in the Dark Energy Survey Nora Shipp, U. Chicago Yuanyuan Zhang We perform a search for stellar streams around the Milky Way using the first three years of multi-band optical imaging data from the Dark Energy Survey (DES). We use DES data covering ∼5000 sq. deg. to a depth of g>23.5 with a relative photometric calibration uncertainty of <1%. This data set yields unprecedented sensitivity to... More »
20180226 Feb. 26, 2018, 2:00 pm Stellar Streams Discovered in the Dark Energy Survey Nora Shipp, U. Chicago We perform a search for stellar streams around the Milky Way using the first three years of multi-band optical imaging data from the Dark Energy Survey (DES). We use DES data covering ∼5000 sq. deg. to a depth of g>23.5 with a relative photometric calibration uncertainty of <1%. This data set yields unprecedented sensitivity to... More »
20180305 March 5, 2018, 2:00 pm TBD Kimberly Boddy, Johns Hopkins
20180319 March 19, 2018, 2:00 pm Intensity Interferometry in the Era of Giant Telescopes Albert Stebbins, FNAL Three widely separated 30m class optical telescopes (E-ELT, GMT, TMT) will start observations in the coming decade and will provide a new opportunity to probe moderately dim sources with unprecedented angular resolution using the spectroscopic count intensity interferometry technique (see Hanbury Brown and Twiss).  The large baselines which extend up to 10,000 km probe angular... More »
20180326 March 26, 2018, 2:00 pm TBD Michael Cooper, UC Irvine
20180402 April 2, 2018, 2:00 pm TBD Mike Boylan-Kolchin, UT Austin
20180409 April 9, 2018, 2:00 pm TBD Andrew Long, U. Chicago KICP
20180416 April 16, 2018 No Seminar (APS Meeting) N/A
20180423 April 23, 2018, 2:00 pm TBD Mark Devlin, UPenn
20180430 April 30, 2018, 2:00 pm TBD Heidi Wu
20180507 May 7, 2018, 2:00 pm TBD Jason Detwiler, U Wisconsin Madison
20180521 May 21, 2018, 2:00 pm TBD Brian Keating, UC San Diego
20180530 May 30, 2018, 2:00 pm Galaxy cluster mass measurements in the Dark Energy Survey Tom McClintock, University of Arizona Galaxy clusters are a powerful probe of cosmological parameters and host up to hundreds of galaxies. These clusters reside in massive dark matter halos, which are virialized structures comprised of up to a few times 10^15 solar masses. Forming the foundation of galaxy cluster cosmology are two critical components: measurements of cluster masses, and models... More »
20180604 June 4, 2018, 2:00 pm Anisotropies in the Gravitational Wave Background from Cosmological Phase Transitions Yuhsin Tsai, U Maryland Phase transitions in the early universe can readily create an observable stochastic gravitational wave background. I will argue that such a background necessarily contains anisotropies analogous to those of the cosmic microwave background (CMB) of photons, and that these too may be within reach of proposed gravitational wave detectors. Correlations within the gravitational wave anisotropies... More »
20180611 June 11, 2018, 2:00 pm The Linear Point: a cleaner cosmological standard ruler in the galaxy correlation Stefano Anselmi, Observatoire de Paris Cosmology has made fundamental progress thanks to the role of standard rulers: objects of known size that are constant in redshift. The acoustic peak in the large scale structure clustering correlation function is one of them. However, in the era of precision cosmology, its power has been highly challenged by late time non-linear effects that... More »
20180618 June 18, 2018, 2:00 pm TBD Oren Slone, Princeton
20180625 June 25, 2018, 2:00 pm TBD Julio Navarro, U Victoria
20180709 July 9, 2018, 2:00 pm A New Frontier in the Search for Dark Matter  Gordan Krnjaic, Fermilab The gravitational evidence for the existence of dark matter is overwhelming; observations of galactic rotation curves, the CMB power spectrum, and light element abundances independently suggest that over 80% of all matter is “dark” and beyond the scope of the Standard Model. However, its particle nature is currently unknown, so discovering its potential non-gravitational interactions... More »
20180730 July 30, 2018, 2:00 pm TBD Jia Liu, UChicago
20180806 Aug. 6, 2018, 2:00 pm TBD Robert Nemiroff, MTU
20180808 Aug. 8, 2018, 2:00 pm TBD (Note different day) Francesco Navarro
20180813 Aug. 13, 2018, 2:00 pm TBD Asher Berlin, SLAC
20180813 Aug. 13, 2018, 2:00 pm Massive Gravity and Cosmology Rachel Rosen, Columbia
20180917 Sept. 17, 2018, 2:00 pm TBD Eduardo Rozo, Arizona
20180924 Sept. 24, 2018, 2:00 pm TBD Kate Scholberg, Duke
20181001 Oct. 1, 2018, 2:00 pm TBD Julian Munoz, Harvard
20181015 Oct. 15, 2018, 2:00 pm TBD Yao-Yuan Mao, Pittsburgh
20181029 Oct. 29, 2018, 2:00 pm TBD Suzanne Staggs, Princeton
20181105 Nov. 5, 2018, 2:00 pm Dark matter axion clumps Mark Hertzberg, Tufts In this talk I begin by reviewing how dark matter axions can undergo Bose-Einstein condensation and why this is captured by classical field theory. I explain that such condensates are spatially localized clumps, as they are organized by gravitation and self-interactions, and they may populate the galaxy. I discuss both the ground state and finite... More »
20181112 Nov. 12, 2018, 2:00 pm TBD Reyco Henning, UNC Chapel Hill
20181119 Nov. 19, 2018, 2:00 pm TBD Raymond Co, Michigan
20181126 Nov. 26, 2018, 2:00 pm TBD Deanna Hooper, Aachen University Dan Hooper
20181203 Dec. 3, 2018, 2:00 pm TBD Anson Hook, University of Maryland, College Park Gordan
20181210 Dec. 10, 2018, 2:00 pm TBD Hongwan Liu, MIT TBD
20181217 Dec. 17, 2018, 2:00 pm TBD Nilanjan Banik, Amsterdam/Leiden
20190218 Feb. 18, 2019, 12:00 pm TBA Ken Van Tilburg, NYU/IAS
20190218 Feb. 18, 2019, 2:00 pm Cosmic Ray Anti-nuclei and Dark Matter Ilias Cholis, Oakland University Antimatter cosmic ray measurements are used to advance our understanding of high energy astrophysical phenomena in the Galaxy. Using the antiproton cosmic ray measurements by the Alpha Magnetic Spectrometer (AMS) onboard the International Space Station, I will present work in search of unexpected sources of antiprotons. I will discuss the uncertainties related to the interstellar... More »
20190225 Feb. 25, 2019, 2:00 pm TBA Christine Simpson, University of Chicago (KICP)
20190304 March 4, 2019, 2:00 pm TBA Yu-Dai Tsai, Fermilab
20190311 March 11, 2019, 2:00 pm TBA Rebecca Leane, MIT
20190325 March 25, 2019, 2:00 pm TBA Arran Phipps
20190408 April 8, 2019, 2:00 pm TBA Adam Anderson, Fermilab
20190415 April 15, 2019, 2:00 pm TBA Kohta Murase, Penn State
20190422 April 22, 2019, 2:00 pm TBA Mustafa Amin, Rice University
20190708 July 8, 2019, 2:00 pm Neutrino Flavor Mixing in Core-Collapse Supernovae Mackenzie Warren, Michigan State University Sam McDermott Core-collapse supernovae, the explosive deaths of massive stars, remain some of the largest computational simulations in astrophysics – requiring careful treatment of general relativity, magento-hydrodynamics, nuclear physics, and neutrino transport and interactions. Despite increasing physical fidelity, modern simulations of core-collapse supernovae still don’t self- consistently account for the effects of neutrino flavor mixing. Such effects... More »
20190715 July 15, 2019, 2:00 pm Enhancing the Scan Rate of a Dark Matter Axion Search: Quantum Noise Evasion and Maximally Informative Analysis Daniel Palken, JILA / University of Colorado, Boulder Gordon Krnjaic Abstract: Putative axion particles are well motivated solutions to the outstanding mystery of the universe’s dark matter, yet their extremely feeble coupling to ordinary matter makes them difficult to detect. The axion haloscope, first realized experimentally three decades ago, remains among the most viable detection platforms, but even today’s leading technology would take many of... More »
20190722 July 22, 2019, 2:00 pm Probing Dark Matter and Dark Energy with Strong Gravitational Lensing Simon Birrer, University of California, Los Angeles Gordon Krnjaic Evidence from different cosmological probes have lead to the establishment of the dark matter and dark energy paradigm. Dark matter dominates the matter budget at cosmological scales and drives the formation of structure and dark energy is responsible for the late time acceleration of the universe. In my talk, I will describe how we use... More »
20190729 July 29, 2019, 2:00 pm The Emerging Population of Gravitational Wave Sources Will Farr, Stony Brook University / Center for Computational Astrophysics, Flatiron Institute Gordan Krnjaic Abstract:  The last four years have been a bonanza for gravitational wave astronomy.  The first gravitational wave signal ever detected—GW150914, the merger of a 30- and a 40-solar mass black hole—was followed by nine more announced black hole mergers in Advanced LIGO’s first and second observing runs (several were also observed in the Virgo detector). ... More »
20190802 Aug. 2, 2019, 2:00 pm Pushing Neutrino Physics to the Cosmic Frontier Mauricio Bustamante, Niels Bohr Institute, University of Copenhagen, Denmark Gordan Krnjaic Abstract: There is vast potential in high-energy cosmic neutrinos to test particle physics. The cosmic neutrinos recently discovered by IceCube have the highest detected neutrino energies – up to a few PeV – and travel the longest distances – up to a few Gpc, the size of the observable Universe. These features make them attractive... More »
20190805 Aug. 5, 2019, 2:00 am Pulsar Timing as a Probe of Primordial Black Holes and Subholes Jeff Dror, Lawrence Berkeley National Laboratory Gordon Krnjaic Abstract: Pulsars act as accurate clocks, sensitive to gravitational redshift and acceleration induced by transiting clumps of matter. In this talk, I study the sensitivity of pulsar timing arrays (PTA) to transiting compact dark matter objects, focusing on primordial black holes and subhalos. Such dark matter clumps can result in different classes of signals observable in pulsar timing experiments depending on the... More »
20190812 Aug. 12, 2019, 2:30 pm Multiwavelength Dark Matter Searches Tesla Profumo, University of California, Santa Cruz The nature of the dark matter particle and what underlying particle physics model it relates to remain unknown.  I will describe multi-pronged, astronomical investigations of both WIMP and non-WIMP dark matter candidates using radio, X-ray, and gamma-ray data.  These studies include tests of the potential dark matter origin of galactic gamma-ray signals in our Galaxy... More »
20190819 Aug. 19, 2019, 2:00 pm Axion Dark Matter Detection with CMB Polarization Michael Fedderke, Stanford University / University of California - Berkeley / LBNL Gordon Krnjaic Abstract: In this talk, I will detail two ways to search for low-mass axion dark matter using cosmic microwave background (CMB) polarization measurements. These appear, in particular, to be some of the most promising ways to directly detect fuzzy dark matter. Axion dark matter causes rotation of the polarization of light passing through it. This... More »
20190820 Aug. 20, 2019, 2:00 pm TeV Dark Matter Search Program with the Cherenkov Telescope Array: The Strategy and Synergies with Current Gamma-Ray Experiments Gabrijela Zaharijas, Univ. of Nova Gorica, Slovenia Abstract: High-energy gamma rays are among the most promising tools to constrain or reveal the nature of dark matter, in particular the Weakly Interacting Massive Particles (WIMP) models.  The Cherenkov Telescope Array (CTA) is well into its pre-construction phase and will soon probe the high-energy gamma-ray sky in the 20 GeV – 300 TeV energy range.  Thanks... More »
20190826 Aug. 26, 2019, 2:00 pm Baryogenesis and Dark Matter from B Mesons Miguel Escudero Abenza, King's College London In this talk, based on arXiv:1810.00880, I will present a new mechanism of Baryogenesis and dark matter production in which both the dark matter relic abundance and the baryon asymmetry arise from neutral B meson oscillations and subsequent decays. In the early Universe, decays of a long lived particle produce B mesons and anti-mesons out... More »
20190909 Sept. 9, 2019, 2:00 pm A 1700 km/s Hyper Velocity Star discovered by the Southern Stellar Stream Spectroscopic Survey Ting Li, Carnegie Observatories In this talk, I will present an ongoing spectroscopic program, the Southern Stellar Stream Spectroscopic Survey (S5), which maps these southern streams with the fiber-fed AAOmega spectrograph on the Anglo-Australian Telescope. S5 is the first systematic program pursuing a complete census of known streams in the southern hemisphere. In additional to observing stars in the... More »
20190916 Sept. 16, 2019, 2:00 pm Machine Learning Dark Matter Halo Formation Luisa Lucie-Smith, University College London Dark matter halos are the fundamental building blocks of cosmic large-scale structure. Improving our theoretical understanding of their structure, evolution and formation is an essential step towards understanding how galaxies form. Although N-body simulations are the only tool to fully compute the non-linear gravitational evolution of halos, it is difficult to gain physical interpretation from... More »
20190923 Sept. 23, 2019, 2:00 pm Searching for Quantum Structures in Axion Dark Matter Erik Lentz, Georg-August Universitaet Goettingen Axions and axion-like particles are becoming increasingly attractive candidates for the dark matter. Likewise, searches for these candidates are growing in sophistication, number, reach, and may span much of the candidates’ viable parameter space in the next decade. Many of these searches are capable of extracting detailed knowledge of the local axion distribution, and may... More »
20190930 Sept. 30, 2019, 2:00 pm Toward the Future of Gravitational-Wave Cosmology and More Hsin-Yu Chen, Harvard University Advanced LIGO-Virgo have detected tens of stellar mass compact binary mergers, including binary black holes, binary neutron stars, and potentially neutron star-black hole mergers. In this talk I will focus on a few topics we can learn from these binary mergers: the electromagnetic counterparts of gravitational-wave events, the nuclear equation-of-state, and cosmology. I will first... More »
20191009 Oct. 9, 2019, 2:00 pm Measuring the Hubble Constant using Strongly Lensed Quasars Anowar Shajib, UCLA The recent tension between early- and late-Universe measurements of the Hubble constant highlights the necessity for independent and precise methods such as the time-delay cosmography. The measured time-delays between the lensed images of a background quasar depend on the absolute physical scales in the lens configuration. Thus, the time-delays allow measurements of these scales to infer... More »
20191014 Oct. 14, 2019, 2:00 pm Signatures of the Early Universe in the BAO Spectrum Benjamin Wallisch, UC-San Diego Abstract: Due to theoretical developments and an increase in survey sensitivity, these measurements can now be complemented by large-scale structure observations. In this talk, I will advocate the spectrum of baryon acoustic oscillations (BAO) as a new observable for early universe cosmology beyond its use as a standard ruler. I will present the first measurement... More »
20191017 Oct. 17, 2019, 1:00 pm Exceptionally Heavy Dark Matter Nadav Outmezguine, Tel-Aviv University Abstract: In models where dark matter relic abundance is set by standard thermal freeze-out mechanism, perturbative unitarity bounds require its mass to be below few hundreds TeV. We propose a new thermal freeze-out mechanism, resulting in dark matter mass up to roughly a million TeV, without violating unitarity bounds and without modifying the standard cosmological history.
20191021 Oct. 21, 2019, 3:00 pm Making Dark Matter out of Light: The Cosmology of sub-MeV Freeze-In Katelin Schutz, Massachusetts Institute of Technology Dark matter could be a “thermal-ish” relic of freeze-in, where the dark matter is produced by extremely feeble interactions with Standard Model particles dominantly at low temperatures. In this talk, I will discuss how sub-MeV dark matter can be made through freeze-in, accounting for a dominant new channel where the dark matter gets produced by... More »
20191028 Oct. 28, 2019, 2:00 pm The Future of Massively Multiplexed Spectroscopy: The Maunakea Spectroscopic Explorer Jennifer Marshall, Texas A&M University Results from modern wide-field astronomical imaging surveys have highlighted the need for large aperture, massively multiplexed spectroscopic followup facilities in the optical and near-Infrared wavelength regimes. Such a facility is the most obvious missing link in the emerging network of ground-based observational facilities world-wide. The Maunakea Spectroscopic Explorer (MSE) is a planned 11-m telescope facility... More »
20191104 Nov. 4, 2019, 2:00 pm Diversity in Density Profiles of Self-Interacting Dark Matter Satellite Halos Chih-Liang Wu, Massachusetts Institute of Technology Self-interacting Dark Matter (SIDM) could have a number of striking observable effects, including modifications to the dark matter density on sub-galactic scales. Recent studies have revealed both ultra-compact and ultra-diffuse satellite dwarf galaxies within the Milky Way; I will show that tidal stripping of SIDM satellite halos naturally leads to a wider range of halo... More »
20191111 Nov. 11, 2019, 2:00 pm Conformal Freeze-In Sungwoo Hong, Cornell University Conventionally, the main focus for the cosmic evolution of our universe has been on descriptions in terms of particles: dark matter (DM) as massive particle, and dark radiation, if existing at all, in the form of massless or very light particle. In this talk, I will discuss a scenario where conformal field theory (CFT) plays... More »
20191118 Nov. 18, 2019, 2:00 pm The Accelerated Universe through Weak Lensing Agnès Ferté, Jet Propulsion Laboratory / California Institute of Technology The universe has been going through a phase of accelerated expansion for the last 6 billion years. Understanding the origin of this cosmic acceleration is one of the main goals of observational cosmology: is it caused by a cosmological constant or a dynamical dark energy? Or is it a sign that we don’t understand the... More »
20191125 Nov. 25, 2019, 2:00 pm The Trouble with Hubble: Signs of New Physics? Vivian Poulin, LUPM (CNRS & Université de Montpellier) The value of the Hubble constant as measured using the classical distance ladder method is 4 to 6 sigma higher than the value inferred from a ΛCDM fit to the cosmic microwave background (CMB). Interestingly, we now have several independent local probes of the Hubble constant (supernovae, strongly lensed quasars), such that none of the... More »
20191202 Dec. 2, 2019, 2:00 pm Redshift Inference from the Combination of Galaxy Colors and Clustering in a Hierarchical Bayesian Model Alex Alarcon, Argonne National Laboratory Photometric galaxy surveys constitute a powerful cosmological probe but rely on the accurate characterization of their redshift distributions using only broadband imaging, and can be very sensitive to incomplete or biased priors used for redshift calibration. Several techniques for estimating the redshift distributions of imaging surveys have been developed in the last decades, which can... More »
20191209 Dec. 9, 2019, 2:00 pm Early-Universe Simulations of the Cosmological Axion Malte Buschmann, University of Michigan Abstract: Ultracompact dark matter (DM) minihalos at masses at and below 10^−12 solar masses arise in axion DM models where the Peccei-Quinn (PQ) symmetry is broken after inflation. The minihalos arise from density perturbations that are generated from the non-trivial axion self interactions during and shortly after the collapse of the axion-string and domain-wall network.... More »
20191216 Dec. 16, 2019, 2:00 pm Particle Acceleration in the Cygnus Star Forming Region Binita Hona, Michigan Technological University Massive stars were postulated as sources of cosmic rays (CRs) in our Galaxy since more than three decades ago. GeV photons have been observed by Fermi-LAT from the star-forming region of Cygnus X, showing that young CRs up to TeV are produced and are interacting with the ambient gas and radiation fields. However, the role... More »
20200113 Jan. 13, 2020, 2:00 pm Particle Astrophysics Seminar: Leak-In Dark Matter Cristian Gaidau, University of Illinois I will discuss leak-in dark matter, a novel out-of-equilibrium origin for the dark matter (DM) in the universe. Leak-in DM is a minimal, internally-thermalized, hidden sector populated from an out-of-equilibrium, feeble connection to the hotter standard model (SM) sector. When this connection is renormalizable, the colder sector undergoes an extended phase of non-adiabatic evolution largely... More »
20200127 Jan. 27, 2020, 3:00 pm Particle Astrophysics Seminar: Time-Domain Astrophysics in a Multi-Messenger World Kate Alexander, Northwestern University Time-domain astrophysics provides a unique opportunity to study the most extreme physical processes in the Universe, including the deaths of massive stars, the destruction and creation of compact objects like neutron stars and black holes, and the tidal disruption of stars by supermassive black holes. Recently, with the pioneering detections of gravitational waves, astronomers and... More »
20200203 Feb. 3, 2020, 1:00 pm Particle Astrophysics Seminar: The Inflaton Portal to a Highly Decoupled EeV Scale Dark-Matter: Production Mechanism and Experimental Signatures Lucien Heurtier, University of Arizona In this talk, I will explore the possibility that the dark matter relic abundance is generated in a context where the inflaton is the only mediator between the visible and the hidden sectors of our Universe. I will present a model of highly-decoupled dark matter and show that involving the inflationary sector in the mechanism... More »
20200203 Feb. 3, 2020, 2:00 pm Superradiance Inferences from Black Holes Spins Measured by LIGO and X-Ray Binaries Nicolas Fernandez Gonzalez, University of Illinois (Urbana-Champaign) Black holes are the perfect playground for physics, to search for new ultralight bosons. Bosons can form clouds around rotating black holes if their Compton wavelength is comparable to the black hole size, through a process called superradiance, extracting angular momentum and energy from the black hole and populating an exponentially large number of gravitationally-bound... More »
20200210 Feb. 10, 2020, 2:00 pm Superradiance Inferences from Black Holes Spins Measured by LIGO and X-Ray Binaries Nicolas Fernandez Gonzales, University of Illinois Black holes are the perfect playground for physics, to search for new ultralight bosons. Bosons can form clouds around rotating black holes if their Compton wavelength is comparable to the black hole size, through a process called superradiance, extracting angular momentum and energy from the black hole and populating an exponentially large number of gravitationally-bound... More »
20200217 Feb. 17, 2020, 2:00 pm Cosmological Constraints with Clusters from the SPT-SZ and SPTpol Extended Cluster Surveys Lindsey Bleem, Argonne National Laboratory Clusters of galaxies selected by the Sunyaev-Zel’dovich (SZ) effect are powerful tools with which to constrain cosmological models. Here I will present the latest cosmological results using clusters identified by the South Pole Telescope (SPT) particularly focusing on results from the 2500 deg^2 SPT-SZ and new 2700 deg^2 SPTpol Extended Cluster Survey (SPT-ECS); with the... More »
20200224 Feb. 24, 2020, 2:00 pm Particle Astrophysics Seminar: Classifying High-redshift Merging Galaxies with Deep Neural Networks Aleksandra Ćiprijanović, Mathematical Institute of the Serbian Academy of Sciences and Arts Abstract: Distinguishing between merging and non-merging galaxies in observations can sometimes be a very slow and difficult process. Today, with the availability of large-scale simulations, we have the ability to learn from large samples of labeled images of merging galaxies and transfer that knowledge to search for these objects in the observed data. The task of... More »
20200302 March 2, 2020, 2:00 pm Light Relics in Cosmic Microwave Background Marilena Loverde, Stony Brook University Neutrinos and other light relic particles leave a number of imprints in the cosmic microwave background anisotropies and on maps large-scale structure of the universe. Some of these imprints can not only demonstrate the presence of these particles, but can provide insight into their nature via signatures of interactions or other behavior that changes during... More »
20200309 March 9, 2020, 2:00 pm Searching for Dark Matter with Liquid Scintillators Benjamin Lillard, University of Illinois (Urbana-Champaign) Organic scintillators are a promising and under-developed avenue for the direct detection of sub-GeV dark matter through electron scattering. With eV-scale excitation energies that rival the sensitivity of semiconductor targets, they can be produced in bulk quantities and purified relatively inexpensively. A low-background kilogram-size liquid scintillator target could achieve world-leading sensitivity to sub-GeV dark matter... More »
20200316 March 16, 2020, 2:00 pm Large-Scale Structure Cosmology with AI-Accelerated Forward Modeling Andrew Hearin, Argonne National Laboratory Present-day and near-future galaxy surveys create the capability to measure cosmological structure growth using multiple, distinct populations of galaxies as tracers of the underlying density field. Multi-tracer cross-correlations contain rich information that can be used to self-calibrate systematics and significantly enhance cosmological constraining power. However, conventional theoretical models for making these predictions bear the mark... More »
20200323 March 23, 2020, 2:00 pm A New Mask for An Old Suspect: Testing the Sensitivity of the Galactic Center Excess to the Point Source Mask Yiming Zhong, UChicago The Fermi-LAT collaboration has recently released a new point source catalog, referred to as 4FGL. For the first time, we perform a template fit using information from this new catalog and find that the Galactic center excess is still present. On the other hand, we find that a wavelet-based search for point sources is highly... More »
20200330 March 30, 2020, 2:00 pm CrystaLiZe: A Solid Future for LZ Scott Kravitz, Lawrence Berkeley National Laboratory Radon and its daughter decays limit the sensitivity of direct WIMP dark matter searches, despite extensive screening programs, careful material selection and specialized Rn-reduction systems. For xenon time projection chambers, a means to surpass this constraint may lie in crystallizing the xenon. In a solid matrix, each of the decay steps surrounding the problematic radon... More »
20200413 April 13, 2020, 1:00 pm Particle Astrophysics Seminar: Dark matter from scalar field fluctuations Tommi Tenkanen, Johns Hopkins University Abstract: The observed dark matter (DM) abundance in the Universe can be fully accounted for by a minimally coupled spectator scalar field that was light during cosmic inflation. In this scenario, dark matter was produced during inflation by amplification of quantum fluctuations of the spectator field. I will discuss the DM isocurvature perturbations that are... More »
20200420 April 20, 2020, 2:00 pm Particle Astrophysics Seminar: Primordial Black Hole Dark Matter and Ways to Find It Volodymyr Takhistov, UCLA Abstract: Primordial black holes (PBHs) constitute an attractive candidate for dark matter. I will describe a new generic mechanism for PBH formation from fragmentation of scalar fields, which allows to produce PBHs with high spin. I will then revisit another general formation mechanism, from vacuum bubbles during inflation, and show how the resulting broad PBH... More »
20200427 April 27, 2020, 2:00 pm Particle Astrophysics Seminar: Talks, sure, but how? Making the case for prerecorded science talks. Knud Jahnke, Max Planck Institute for Astronomy For more information, please join the FCPA mailing list.
20200504 May 4, 2020, 2:00 pm Particle Astrophysics Seminar: New Channels in the Search for Dark Matter Daniel Baxter, University of Chicago Abstract:  In direct detection experiments, interpreting an observed rate as a limit on (or detection of) dark matter requires assumptions about the type of interaction. Typically, this breaks down as elastic nuclear scattering (for energies >1 keV) or electron scattering (for energies 1-50 eV). The first challenge to this conventional way of thinking came in... More »
20200511 May 11, 2020, 2:00 pm Particle Astrophysics Seminar: Strongly Interacting Dark Matter Hitoshi Murayama, Berkeley Abstract: Dark Matter may not be an elementary particle but rather bound states of strong interactions similar to hadrons in QCD.  It is actually desirable if we want dark matter to be self-interacting to address the core/cusp issue.  It could be dark pions that undergo freeze-out by 3->2 annihilation.  It could also be dark baryons that... More »
20200518 May 18, 2020, 2:00 pm Particle Astrophysics Seminar: The bright future of cosmology with SPT-3G Amy Bender, Argonne National Laboratory Abstract: Observations of the cosmic microwave background (CMB) probe a diverse set of fundamental physics in both the early and late universe.  CMB measurements are a cornerstone of our now exceptionally precise Lambda-CDM model of cosmology, however, many questions remain.  Did an inflationary epoch occur a fraction of a second after the Big Bang?  What... More »