Bulletin of the American Physical Society
86th Annual Meeting of the APS Southeastern Section
Volume 64, Number 19
Thursday–Saturday, November 7–9, 2019; Wrightsville Beach, North Carolina
Session F01: Multimessenger Astrophysics II |
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Chair: Imre Bartos, University of Florida Room: Holiday Inn Resort Causeway/Masonboro |
Friday, November 8, 2019 10:30AM - 11:00AM |
F01.00001: Relativistic Shapiro delay measurements of a 2.14-solar-mass millisecond pulsar Invited Speaker: Thankful Cromartie Millisecond pulsar (MSP) timing — the process of accounting for every rotation of a rapidly spinning neutron star over long time spans — is a powerful tool for probing realms of physics that are otherwise inaccessible to Earth-based scientists. The neutron star interior equation of state (EoS) is one example of a puzzle in fundamental physics that has been somewhat elucidated by MSP timing. Measuring relativistic Shapiro delay, which is observable in a small subset of MSP binaries, facilitates the unique determination of the masses of both a pulsar and its companion. By combining orbital-phase-specific observations of Shapiro delay using the Green Bank Telescope with data from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) 12.5-year data set, we have measured the mass of PSR J0740$+$6620 to be 2.14 ($+$0.10, $-$0.09) solar masses (68\% credibility interval); it is therefore likely to be the most massive neutron star yet observed. Our measurements serve as a strong constraint on the neutron star interior EoS. [Preview Abstract] |
Friday, November 8, 2019 11:00AM - 11:30AM |
F01.00002: Multi-messenger probes of the neutron star equation of state Invited Speaker: Zach Carson The gravitational wave emission from the merging binary neutron star system GW170817 arrived full of tidal information which can be used to probe the fundamental ultra-dense nuclear physics residing in these stars. Similarly, the X-ray observations of low-mass neutron star binaries found in globular clusters allow us to further probe this physics, particularly useful in measuring the neutron star radius. By combining these multi-messenger observations as prior knowledge, we find correlations between the neutron star radius, tidal deformability, and the nuclear matter parameters deterministic of the neutron star equation of state. We find such correlations for varying chirp masses, the dominant determining factor in the frequency evolution of the inspiral, so that one can apply the same method to future detections. We estimate how accurately one can measure nuclear parameters with future gravitational wave interferometers and show how such measurements can be improved by combining multiple events. [Preview Abstract] |
Friday, November 8, 2019 11:30AM - 12:00PM |
F01.00003: Supermassive Black Hole Demographics In The Era Of Multimessenger Pulsar Timing Array Detection Invited Speaker: Stephen Taylor Supermassive black holes lurk at the centers of massive galaxies, and are themselves the most massive compact objects in the Universe. Over cosmic time, galaxies grow through accretion and mergers, such that in the post-merger phase they harbor two supermassive black holes that spiral toward coalescence through a variety of dynamical processes. The subset of these with 108 - 1010 solar masses and orbital periods of several years form the target population for pulsar- timing array (PTA) experiments such as the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) and the International Pulsar Timing Array (IPTA). PTAs search for nanohertz gravitational-wave signals through induced Doppler shifts to the arrival rate of radio-pulses from millisecond pulsars. Many candidate binaries have been found through traditional electromagnetic means, although the only system with confidently detected multiple radio cores is too widely separated for PTAs to detect. Likewise, the quasi-variability of AGN in various photometric surveys (e.g. CRTS, PTF, and PanSTARRS) has produced many candidates, but none whose variability is unambiguously tied to the presence of a binary. I will review current efforts to find binary supermassive black holes through PTA searches and targeted multi- messenger campaigns, then discuss what current constraints and future detections can unveil about massive black hole demographics and the growth of galaxies. [Preview Abstract] |
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