Bulletin of the American Physical Society
19th Annual Meeting of the APS Northwest Section
Volume 63, Number 6
Thursday–Saturday, May 31–June 2 2018; Tacoma, Washington
Session C1: Astronomy and Cosmology II |
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Chair: Bennett Link, Montana State University Room: Thompson Hall 175 |
Friday, June 1, 2018 3:30PM - 4:00PM |
C1.00001: The Origin of Supermassive Black Holes Invited Speaker: Amy Reines The origin of supermassive black holes remains a major outstanding issue in modern astrophysics. These monster black holes reside in the nuclei of essentially every massive galaxy and power the most luminous quasars at the edge of the observable Universe. However, directly observing the first ``seed'' black holes in the earlier Universe - that can eventually grow to upwards of a billion solar masses - is not feasible with current telescopes. Present-day dwarf galaxies, on the other hand, are within observational reach and offer another avenue to learn about black hole seeds since low-mass galaxies can host relatively pristine black holes. In this talk, I will highlight some of my recent achievements in this field that have taken us from a few rare examples to large systematically-assembled samples of dwarf galaxies hosting nuclear black holes. I will also discuss how my work has implications for directly detecting black hole activity in the first galaxies in the earlier Universe. [Preview Abstract] |
Friday, June 1, 2018 4:00PM - 4:12PM |
C1.00002: Replacing dark matter with a slow force Elizabeth Loggia, Kris Sigurdson Historically, dark matter emerged to explain inconsistencies in general relativity and galaxy rotation curves, and it has since had success through indirect observation. However, after several decades of searching, there have not been any direct detections, and the constraints on dark matter keep increasing. As such, it is important to explore alternatives. One alternative theory is to describe gravity as an entropic force, implying it is an emergent phenomenon rather than a fundamental interaction. This theory serves as motivation for the toy model presented here. Instead of dark matter, we consider an extra force. This force couples to baryonic matter and acts in much the same way that gravity does, but with an important distinction: speed. Where gravitational interactions propagate at the speed of light, the interactions from this new force propagate more slowly. The idea is to explore how this delayed gravity-like force affects the dynamics of baryonic matter that were originally explained via dark matter. Theories associated with dark matter have a rich phenomenology. As the parameter space for dark matter continues to shrink with ongoing experiments, this study will provide important insight into the validity of theories alternative to dark matter. [Preview Abstract] |
Friday, June 1, 2018 4:12PM - 4:24PM |
C1.00003: Noise Analysis of the ADMX Josephson Parametric Amplifier Alyssa Lee, Gray Rybka Axions are hypothetical particles that, if they exist, would solve both the strong CP problem and the dark matter problem. The ADMX experiment is searching for dark matter axions through their conversion to microwave photons in a strong magnetic field. The ability of ADMX to detect these photons is strongly dependent on the the low noise properties of Josephson Parametric Amplifiers (JPA). I will present a preliminary gain and noise analysis of the JPA being used in the 2018 run of ADMX and the resultant effects on the experiment's system noise. [Preview Abstract] |
Friday, June 1, 2018 4:24PM - 4:36PM |
C1.00004: Post-merger: numerical relativity meets turbulence Matthew Duez Compact object binary mergers with neutron stars are detectable both electromagnetically and via gravitational waves, but modeling the post-merger evolution is a difficult general relativistic radiation magnetohydrodynamic (MHD) problem, involving multiple length and time scales. This has driven numerical relativists to pursue strategies for approximately capturing unresolvable turbulent dynamo and transport effects, with consequences for remnant collapses, gamma ray bursts, and outflows. In this talk, I will describe post-merger simulations with neutrinos and MHD carried out by the SXS collaboration and possible strategies for dealing with subgrid scale effects. [Preview Abstract] |
Friday, June 1, 2018 4:36PM - 4:48PM |
C1.00005: Bayesian Reconstructions of Gravitational-wave Bursts Meg Millhouse With several gravitational-wave detections by Advanced LIGO, we are now firmly in the era of gravitational-wave astronomy. So far all of the detected signals have been from coalescing compact objects, namely neutron stars or black holes. These are systems that have been studied in depth, and can be analyzed using general relativity based waveform models. A complementary approach to this is to search for and reconstruct gravitational waves with little to no assumptions on the source of the signal. Unmodeled analyses have the advantage of being able to capture to a wider variety of gravitational-wave sources, though with the disadvantage of being less sensitive than the modeled searches to quieter signals. In this talk I will present a method of reconstructing gravitational-wave bursts using a wavelet decomposition and Bayesian inference, and further discuss how we can use these reconstructions to characterize the signal. [Preview Abstract] |
Friday, June 1, 2018 4:48PM - 5:00PM |
C1.00006: Scheme for Implementing Axisymmetry Using a Multipatch Setup in Numerical Relativity Jerred Jesse With the observation of a kilonova signal following the detection of the binary neutron star merger GW170817, the need for an extended duration simulation of the post-merger environment has become important in order to determine the effects of the stability of the remnant on the observed signal. In order to extend simulation times in the Spectral Einstein Code (SpEC), we have developed a modification to SpEC's multipatch coordinate transformation implementation to allow for easily running a post-merger simulation in axisymmetry. Several tests using simple equilibrium systems both without and with added magnetic fields have shown the viability of this method and demonstrated a significant decrease in required computational resources versus a full 3D simulation. [Preview Abstract] |
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