Seminar archive 2019

Raw date Event date Title Speakers Host Summary Links
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 »