April 5, 2017 | 3:30 PM | ERC 401 News from PICO and COHERENT Juan I. Collar, University of Chicago
Video I will discuss the most recent results from PICO, a search for WIMP dark matter using bubble chambers, as well as future plans and some exciting lines of related research. I will then move on to cover COHERENT, an ongoing effort at ORNL's Spallation Neutron Source to detect and exploit coherent neutrino-nucleus scattering, soon to produce first results. The "glue" between these two subjects will be an elaboration on the overlap in techniques and methods used in modern neutrino and astroparticle physics. Abundant examples of this cross-talk will be provided.
April 19, 2017 | 3:30 PM | ERC 161 Observing, Mapping and Mocking our Cosmic Beginnings J. Richard Bond, Canadian Institute for Theoretical Astrophysics, University of Toronto
Video I will give my take on the phenomenology (and yes theory) of inflation as revealed in Planck and other CMB) and LSS experiments, but with an eye to the glorious CMB future of AdvACT, CCAT-p, Simons Observatory, Stage 4, and the LSS of Euclid, Chime, and much more besides that we mock. Apart from displaying linear and quadratic maps of the primordial universe, a compression of what we now know, i will chat about CMB/LSS anomalies, in practice and in theory, pointing to post-inflation chaotic dynamical systems that can lead to subdominant non-Gaussian signals unlike the ones we have put such stringent constraints on with Planck 2015; and relate everything to non-equilibrium entropies, including the formation of all cosmic structure.
March 31, 2017 | 12:00 PM | ERC 401 Delensing CMB B-modes: results from SPT Alessandro Manzotti, University of Chicago
A promising signature of cosmic inflation is the presence of a "B-mode" component in the polarization of the Cosmic Microwave Background (CMB) induced by primordial gravitational waves. For many inflation models, this B-mode signal is predicted to be at a level detectable in the near future. However current searches are limited by a "lensing B-mode" component that is produced by gravitationally lensing primordial E modes. In order to potentially detect the inflationary signal from B-mode measurements, lensing B modes must be characterized and removed in a process referred to as "delensing." This process has been studied extensively theoretically and with simulations, but has not been performed on polarization data. In this talk, I will present a demonstration of CMB B-mode delensing using polarization data from the South Pole Telescope polarimeter, SPTpol. Furthermore, using realistic simulations that include filtering and realistic CMB noise, we will show what is currently limiting the delensing efficiency and how it will rapidly improve in the near future.
April 7, 2017 | 12:00 PM | ERC 401 Radio-detection of Ultra-High Energy Neutrinos with the ANITA Long-Duration Balloon Payload Cosmin Deaconu, The University of Chicago
The interactions of ultra-high-energy cosmic rays with the Cosmic Microwave Background are expected to produce a flux of EeV-scale neutrinos through the GZK process. Successful detection of these cosmogenic neutrinos would help elucidate the sources of the highest-energy cosmic rays and probe the standard model in a new regime. Due to the low predicted flux and small interaction cross-section, an enormous detector is required for successful measurement. The Antarctic Impulse Transient Antenna (ANITA) long-duration balloon payload scans the Antarctic ice sheet for radio emission produced by the interactions of cosmogenic neutrinos in ice. At altitude, ANITA instantaneously instruments a volume on the order of 10^6 km^3. This talk will provide an overview of the ANITA detection technique, instrumentation, analysis methods, and results so far. I will focus on the recent fourth flight of ANITA, completed in December, as well as a strange event detected in the first ANITA flight that is potentially of neutrino origin.
April 14, 2017 | 12:00 PM | ERC 401 Superfluid 4He as a tool for sub-eV particle physics Scott Hertel, University of Massachusetts
Efforts to observe interactions between galactic dark matter and laboratory test particles are undergoing a transition, broadening out from the standard WIMP hypothesis. Some models newly attracting attention inhabit the keV-MeV mass range. The dominant practical challenge in probing this light mass range is the development of detector technologies sensitive to sub-eV energy depositions. I'll describe both the general challenge of this low-energy regime and also one possible technological path forward, employing meV-scale kinetic excitations of the superfluid state.
April 21, 2017 | 12:00 PM | ERC 401 The Vev Flip-Flop: Dark Matter Decay between Weak Scale Phase Transitions Michael J Baker, Johannes Gutenberg University Mainz
We discuss a new alternative to the Weakly Interacting Massive Particle (WIMP) paradigm for dark matter. Rather than being determined by thermal freeze-out, the dark matter abundance in this scenario is set by dark matter decay, which is allowed for a limited amount of time just before the electroweak phase transition. We discuss a concrete model which exhibits a ``vev flip-flop'' and show that it is phenomenologically successful in the most interesting regions of its parameter space. We comment on detection prospects, primarily at the LHC.
April 28, 2017 | 12:00 PM | ERC 401 Searching for Dark Matter with the Micro-X Sounding Rocket Antonia Hubbard, Northwestern University
The Micro-X sounding rocket uses a Transition Edge Sensor (TES) array to make X-ray observations. The improved energy resolution of TESs compared to traditional space-based X-ray detectors brings new precision to both supernova remnant observations and the X-ray search for sterile neutrino dark matter. Current X-ray observations disagree over the potential presence of a 3.5 keV X-ray line consistent with a sterile neutrino interaction, and Micro-X is in a unique position to establish or refute the presence of this line. I will present the construction status of the instrument and expectations for flight observations, with special emphasis given to the prospects of sterile neutrino studies.
May 5, 2017 | 12:00 PM | ERC 401 Simulations of the WFIRST Supernova Survey and Forecasts of Cosmological Constraints Rebekah A Hounsell, University of California Santa Cruz
The Wide Field InfraRed Survey Telescope (WFIRST) was the highest ranked large space-based mission of the 2010 New Worlds, New Horizons decadal survey. It is now a NASA mission in formulation with a planned launch in the mid-2020's. A primary mission objective is to precisely constrain the nature of dark energy through multiple probes, including Type Ia supernovae (SNe Ia). Within this talk I present the first realistic simulations of the WFIRST SN survey based on current hardware specifications and using open-source tools. I will review different survey strategies with varying time allocations between WFIRST's wide-field channel (WFC) imager and integral field channel (IFC) spectrometer, and predict the dark energy task force figure of merit (DETF FoM) for each strategy. Even without improvements to other cosmological probes, the WFIRST SN survey has the potential to increase the FoM by more than an order of magnitude from the current values.
May 12, 2017 | 12:00 PM | ERC 401 The Physics and Cosmology of TeV Blazars Philip Chang, UW-Milwaukee
April 24, 2017 | 10:30 AM | ERC 419 Quantifying the sensitivity of cosmological data to the neutrino mass hierarchy Martina Gerbino, Oskar Klein Centre for Cosmoparticle Physics - Stockholm University
Present measurements are not able to firmly single out nature's choice for the neutrino mass hierarchy. Consequently, in the absence of a robust measurement of the neutrino mass ordering, a desirable bound on the neutrino mass would be one which does not rely on any assumption (or, to be more precise: that relies on the less informative possible assumption) about the hierarchical distribution of the total mass among the three eigenstates. We will discuss the role of the choice of the prior when assessing the sensitivity of data to the neutrino hierarchy, and introduce a novel method to quantify the sensitivity in the context of Bayesian analysis.
April 24, 2017 | 11:00 AM | ERC 419 Can secret neutrino interactions reconcile cosmology with short-baseline anomalies? Massimiliano Lattanzi, Istituto Nazionale di Fisica Nucleare - Ferrara
The interpretation of anomalies in short-baseline (SBL) neutrino experiments in terms of a light (~ 1 eV mass) sterile neutrino is challenged by cosmological observations, since it implies a complete thermalization of the extra eigenstate nd thus N_eff = 4. Moreover, the neutrino mass bound from the Planck satellite strongly disfavours a mass as large as 1 eV. It has been suggested that secret neutrino interactions could allow to circumvent both issues and reconcile SBL and CMB measurements. I will discuss whether this is actually the case, taking into account the effect of secret interactions in the evolution of cosmological perturbations.
April 27, 2017 | 1:00 PM | ERC 445 Dark Matter Halo Bias from Separate Universe Simulations Titouan Lazeryas, MPA
The large-scale local bias parameters of dark matter halos are essential to describe the statistics of halos and galaxies on large scales, as well as for the halo model of the matter distribution. Using so-called separate universe simulations, we recently obtained precise measurements of the three leading bias parameters. For b2 and b3, these are the most precise measurements to date. We compare our results with bias parameters obtained from two and three points cross-correlation functions and with theoretical predictions from the excursion set peaks (ESP) model. Using the same set of simulations, we further investigate halo assembly bias, i.e. the dependence of the halo bias on properties other than the halo mass. We focus on several halo properties including halo concentration, spin, ellipticity and mass accretion rate and measure assembly bias for both b1 and b2. Results are in good agreement with previous studies for the linear bias. To try and better understand the physical mechanisms behind assembly bias, we also look at the joint dependence of bias on two halo properties in addition to the mass and compare our results to theoretical ones from the ESP.
March 29, 2017 | 3:30 PM | ERC 161 How Black Holes get their Kicks: Dynamical Evolution and Coalescence Steinn Sigurdsson, Penn State
Recent observations have increased interest in the possibilities of a significant population of black hole binaries in the local universe. Natal kicks may play a crucial role in the merger rate of stellar mass black holes. Dynamical evolution can lead to an enhanced interaction rate for compact binaries in dense stellar systems and a distinct and richer population of compact binaries. I discuss some of the issues related to black hole binary formation and coalescence, the issue of retention in globular clusters and possible contribution to the LIGO rate.
April 12, 2017 | 3:30 PM | ERC 161 Probing Chemical Enrichment in the Circumgalactic Medium -- Combining Absorption Spectroscopy and Direct Imaging Observations Hsiao-Wen Chen, University of Chicago
Tremendous progress has been made over the last decade in our empiricaland theoretical understanding of how galaxies form and evolve across cosmic time. In particular, state-of-the-art cosmological simulations can not only match the large-scale statistical properties of galaxies, but they can also successfully reproduce the observed small-scale features of star-forming disks. However, these models have fallen short in matching the empirical properties of diffuse gas, which constitutes 90% of all baryons in the universe, beyond visible galaxy disks and into circumgalactic space. An accurate characterization of the complex physical processes that govern the interactions between star-forming regions and this diffuse circumgalactic medium (CGM) is a critical next step toward a comprehensive understanding of galaxy formation and evolution. In this talk, I will summarize the progress and challenges in CGM studies from traditional absorption-line observations, and discuss future prospects in direct imaging of the CGM around distant galaxies.
April 26, 2017 | 3:30 PM | ERC 161 First results from LIGO: past, present and future Nergis Mavalvala, MIT Note: Refreshments served at 4:30 PM, Hubble Lounge
The Laser Interferometer Gravitational-wave Observatory (LIGO) detected gravitational waves for the first time in 2015. Since then there have been a couple more detections of binary black hole mergers. I will discuss the instruments that made these discoveries, the science so far, and plans for future improvements and upgrades to LIGO.
May 3, 2017 | 3:30 PM | ERC 161 TBA Erik Shirokoff, University of Chicago Note: Refreshments served at 4:45 PM, Hubble Lounge
May 10, 2017 | 3:30 PM | ERC 161 Dust polarization and interstellar turbulence Marc Kamionkowski, Johns Hopkins Note: Refreshments served at 4:45 PM, Hubble Lounge
Perhaps the most surprising result from the Planck satellite is the observation that the E-mode power in the dust polarization is twice that in the B mode. In this talk I will show how the E and B modes in the dust polarization are related to fluctuations in the magnetized interstellar medium. I will argue that the observed E/B ratio, as well as the TE (temperature-polarization) cross-correlation are not easily reconciled with expectations from MHD turbulence. I will then discuss some alternative explanations for the dust-emission patterns seen in the Planck temperature-polarization maps and outline some interesting directions for future related research.
April 11, 2017 | 12:00 PM | ERC 576 Star Formation Near the Supermassive Black Hole Sgr A* Farhad Yusef-Zadeh, Northwestern University
The environment of Sgr A* provides a window to close-up study of star formation under extreme physical conditions. A critical question regarding star formation near supermassive black holes (SMBHs) is whether tidal shear in the vicinity of SMBHs is able to completely suppress star formation or induce star formation. There are currently two modes of star formation that are considered to explain the origin of young stars near Sgr A*. One is the standard cloud-based mode of star formation. The other is disk-based of star formation, which explains the disk of stars orbiting Sgr A*. I will present recent observations and discuss these modes of star formation applied to the region within 0.5 pc of Sgr A* and beyond the nuclear cluster. In addition, I will discuss a viable mechanism to explain the origin of the Fermi bubble resulting from gas accretion onto Sgr A* around the same time that young OB stars were formed near the black hole.
May 30, 2017 | 12:00 PM | ERC 576 CANCELLED AGN-driven outflows at z~2 Alison Coil, University of California, San Diego
AGN-driven outflows are assumed to be a key driver of galaxy evolution, determining the shape of the galaxy stellar mass function at high masses and regulating, perhaps even quenching, star formation as galaxies become quiescent. However, the details of how common this feedback is and how it impacts the host galaxy are generally unclear. I will present new results using Chandra data in the CANDELS and UltraVISTA surveys showing which galaxies host AGN of a given accretion rate and how this correlates with star formation in the host galaxy from z~0 to z~4. I will further present new results from the MOSDEF survey on AGN-driven outflows at z~2, discussing their incidence, kinematics, and physical extent. We find that fast, galaxy-wide AGN-driven outflows are common in typical star-forming galaxies at z~2 and that they likely help regulate star formation at the cosmic peak of galaxy growth.
May 30, 2017 | 3:00 PM | ERC 576 CANCELLED Unconscious Bias: How It Works and How to Counter It Alison Coil, University of California, San Diego Note: Unconscious or implicit bias is a preference for groups that operates outside of our awareness and is based on stereotypes or attitudes that we hold and have been taught. I will present results from a variety of studies that show how unconscious bias play
Unconscious or implicit bias is a preference for groups that operates outside of our awareness and is based on stereotypes or attitudes that we hold and have been taught. I will present results from a variety of studies that show how unconscious bias plays out, and how systemic it is, with a focus on academia. While I will mainly discuss faculty hiring, I will also touch on graduate admissions, review panels, recommendation letters, and interruptions during talks. I will discuss how the use of rubrics can help counter unconscious bias and other techniques to use when evaluating candidates.