Cosmology Lunchtime Seminar

semester, 2019


Monday, January 28th 2019
12:20 pm:
Speaker: TBD

Monday, February 4th 2019
12:15 pm:
Speaker: Eliu Huerta
Subject: Convergence of gravitational wave astrophysics, large scale astronomical surveys and data science: A gateway for discovery in the Multi-Messenger Astrophysics Era
MifA faculty candidate

The next decade promises fundamental new scientific insights and discoveries from Multi-Messenger Astrophysics, enabled through the convergence of large scale astronomical surveys, gravitational wave astrophysics, deep learning and large scale computing. In this talk I describe a Multi-Messenger Astrophysics science program, and highlight recent accomplishments at the interface of gravitational wave astrophysics, numerical relativity and deep learning. I discuss the convergence of this program with large scale astronomical surveys in the context of gravitational wave cosmology. Future research and development activities are discussed, including a vision to leverage data science initiatives at the University of Minnesota through transdisciplinary research to spearhead, maximize and accelerate discovery in the nascent field of Multi-Messenger Astrophysics.


Monday, February 11th 2019
12:15 pm:
Speaker: Jennifer Barnes, Columbia University
Subject: Panning for gold with things that go bang in the night
MifA faculty candidate

Electromagnetic follow-up observations of the gravitational wave-detected binary neutron star merger (NSM) GW1701817 suggested that material ejected from the accretion disk formed in the merger underwent a robust r-process nucleosynthesis, producing heavy elements like Au, Pt, and Eu. These observations seemed to answer a long-standing question about the origin of the heaviest elements in the Universe. However, the conditions that characterize the disks formed in NSMs are also found in other systems, raising the question of whether mergers are unique sites of r-process production. Of particular interest for this question is the collapse of rapidly-rotating massive stars, called "collapsars." Like NSMs, collapsars form accretion disks around stellar mass compact objects and are associated with ultrarelativistic outflows that give rise to gamma-ray bursts, similarities that suggest they may also host an r-process. I will review the theoretical progress that allowed the identification of the emission accompanying GW170817 as a specifically r-process-powered transient. I will then discuss recent work that explores whether collapsar disks could successfully produce the r-process, and what the signs of collapsar disk r-process nucleosynthesis might be. I will conclude by highlighting upcoming advances that will allow us to make progress on understanding of r-process origins and other mysteries of the multi-messenger era.


Monday, February 18th 2019
12:15 pm:
Speaker: TBD

Monday, February 25th 2019
12:15 pm:
Speaker: TBD

Monday, March 4th 2019
12:15 pm:
Speaker: TBD

Monday, March 11th 2019
12:15 pm:
Speaker: TBD

Monday, March 18th 2019
12:15 pm:
Spring Break - no seminar this week.

Monday, March 25th 2019
12:15 pm:
There will be no seminar this week.

Monday, April 1st 2019
12:15 pm:
Speaker: Nicholas Mast, UMN
Subject: CDMS Detector Characterization

Monday, April 8th 2019
12:15 pm:
Speaker: Lindsey Bleem, Argonne National Laboratory
Subject: Galaxy Cluster Cosmology with the South Pole Telescope

The South Pole Telescope (SPT) is a 10-meter millimeter-wavelength telescope located at the geographic South Pole, one of the world’s premier sites for millimeter-wave observations. It has been used to survey approximately 1/8 of the sky with arcminute-scale resolution over the course of the 3 surveys: the 2500-square-degree SPT-SZ survey, the 2700-square-degrees SPTpol Extended Cluster Survey, and the 500-square-degree SPTpol main survey (which reached depths of 5.3 uK-arcmin at 150 GHz, 3x deeper than SPT-SZ and 6x deeper than the wide area SPTpol survey). One of the primary objectives of these wide-area surveys has been the construction of a mass-limited sample of galaxy clusters identified via the thermal Sunyaev- Zel’dovich (SZ) effect, through which massive clusters imprint subtle temperature distortions on the cosmic microwave background. The abundance of such clusters is a powerful cosmological probe as it depends sensitively upon both the expansion history of the universe and the growth of density fluctuations. In this talk I will discuss progress analyzing these three datasets including updated cosmological constraints from the initial SPT-SZ cluster sample using weak gravitational lensing data from the Magellan and Hubble Space Telescopes as well as ongoing work from a new project characterizing the strong gravitational lensing properties of these systems in both observations and simulations. The results presented in this talk will be significantly improved with data from the ongoing SPT-3G survey that will identify an order of magnitude more clusters than previous generation SZ surveys.


Monday, April 15th 2019
12:15 pm:
Speaker: Keith Bechtol, University of Wisconsin - Madison
Subject: Dark Matter Science in the LSST Era

Astrophysical observations probe the physics of dark matter through its impact on structure formation throughout cosmic history. On large scales, current observational data are well described by a simple model of stable, non-relativistic, collisionless, cold dark matter (CDM). However, many viable theoretical models of dark matter predict deviations from CDM that are testable with current and future observations. Fundamental properties of dark matter — e.g., particle mass, self-interaction cross section, coupling to the Standard Model, and time evolution — can imprint themselves on the macroscopic distribution of matter in a detectable manner. With supporting theoretical efforts and follow-up observations, LSST will be sensitive to several distinct classes of dark matter models, including particle dark matter, field dark matter, and compact objects. I will discuss several astrophysical probes of dark matter microphysics that can be pursued with LSST, as well as synergies between LSST and other astronomical, cosmological, and particle physics experiments of the 2020s.


Monday, April 22nd 2019
12:15 pm:
Speaker: Andrew Wetzel, UC Davis
Subject: Simulating the Milky Way and its Satellites

I will present the Latte suite of cosmological zoom-in baryonic simulations that model the formation of Milky Way-like galaxies at parsec-scale resolution, using the FIRE (Feedback in Realistic Environments) model for star formation and feedback. First I will discuss the formation of the Milky Way, including the origin of its thin+thick stellar disk morphology, new insights into the elemental abundances of its stellar populations, and connections to recent Gaia observations of the stellar halo. The Latte simulations also self-consistently resolve the formation of satellite dwarf galaxies around each Milky Way-like host. These low-mass galaxies have presented significant challenges to the cold dark matter model, but I will show progress in addressing the "missing satellites" and "too-big-to-fail" problems. Finally, I will discuss synthetic Milky Way surveys that we have created from the Latte simulations, which are publicly available to provide theoretical modeling insight for the era of Gaia.


Monday, April 29th 2019
12:15 pm:
Speaker: Patrick Kelly, Univeristy of Minnesota
Subject: Observing Young Supernovae Early and Often

Since they occur infrequently in specific galaxies, supernovae (SNe)have been difficult to observe within minutes or hours of explosion. The early light curves of SNe, however, contain uniquely constraining information about the size and structure of the stellar progenitor, the presence of a companion revealed through collision the SN ejecta,and, for core-collapse SNe, the arrival of the shockwave at the progenitor's surface. Likewise, spectroscopic observations of SNe within hours or days of explosion can reveal the composition of the progenitor's wind prior to the explosion, since the wind becomes ionized due to the emerging shock. I will discuss progress towards early and high-candence observations of SNe, including those acquired by the Kepler and Transiting Exoplanet Survey Satellite (TESS) missions.


Monday, May 13th 2019
12:20 pm:
There will be no seminar this week.

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