Bulletin of the American Physical Society
APS April Meeting 2019
Volume 64, Number 3
Saturday–Tuesday, April 13–16, 2019; Denver, Colorado
Session Q16: Neutron Star Merger Outflows and Prospects for Observing Them |
Hide Abstracts |
Sponsoring Units: DAP DGRAV Chair: Carolyn Raithel, University of Arizona Room: Sheraton Grand Ballroom I |
Monday, April 15, 2019 10:45AM - 10:57AM |
Q16.00001: HMNS Disk Outflows and the Blue Kilonova from GW170817 Steven Fahlman, Rodrigo Fernandez The recent detection of the first neutron star (NS) merger in gravitational and electromagnetic waves allows us to compare observational data to theoretical predictions. The observed kilonova from GW170817 was powered by the decay of r-process elements ejected from the system, with the light curve depending on the velocity, mass, and composition of the ejecta. Standard kilonova fits require a separate blue component from lanthanide-poor ejecta. The existence of this component has been used as evidence for a hypermassive NS (HMNS) remnant in GW170817. I will present results from long-term hydrodynamic simulations of the accretion disk around a HMNS that for the first time scan a wide range of plausible parameters compatible with GW170817. We find that large outflow velocities (~0.25c) needed to account for the blue kilonova component, cannot be reproduced by a combination of neutrino heating, viscous angular momentum transport, and nuclear recombination. Viable resolutions to this problem are inclusion of magnetic stresses in long-term disk simulations, improved radiative transfer models for kilonova light curve fitting, or enhancements in the dynamical ejecta from merger simulations. |
Monday, April 15, 2019 10:57AM - 11:09AM |
Q16.00002: Viewing angle of binary neutron star mergers Hsin-Yu Chen, Salvatore Vitale, Ramesh Narayan The joint detection of the gravitational wave (GW) GW170817 and its electromagnetic (EM) counterparts has triggered extensive study of the EM emission of binary neutron star mergers (BNSs). |
Monday, April 15, 2019 11:09AM - 11:21AM |
Q16.00003: A neutrinosphere model for kilonova photometry Jessica Meztger, James Annis Models of the electromagnetic emission from a binary neutron star merger are interesting and useful in deducing properties of the merger. We present a unified, physically motivated kilonova model for the UV to IR lightcurves. We develop a neutrinosphere model to parametrize the ejecta composition, and account for ejecta anisotropy and viewing angle effects in producing the observed lightcurves. We are able to describe the data from GW170817, and present fits of the UV to IR lightcurves. Our total inferred ejecta mass of 0.075 solar masses agrees roughly with that inferred by previous models, but the mass ratios of our lanthanide-rich (i.e. “red'') to lanthanide-poor (i.e. “blue'') components is somewhat higher. The velocity of our lanthanide-rich component, 0.27c, is much higher than that inferred by previous models. We also fit blackbodies to the early-time optical photometry, accounting for the blueshift of the expanding ejecta. Our velocity and temperature fits are slower and, for the most part, colder than previous estimates. |
Monday, April 15, 2019 11:21AM - 11:33AM |
Q16.00004: Long-term GRMHD Simulations of Neutron Star Merger Accretion Disks Rodrigo Fernandez, Alexander Tchekhovskoy, Eliot Quataert, Francois Foucart, Daniel Kasen Neutron star mergers result in the formation of an accretion disk that evolves on timescales much longer than the orbital time, thereby ejecting mass that contributes to the r-process kilonova transient. It is widely accepted that angular momentum transport in astrophysical disks is mediated by magnetic turbulence, but thus far very few simulations of these disks have included this effect. I will present results of three-dimensional GRMHD simulations of neutron star merger accretion disks around Kerr black hole remnants, evolved for long enough to achieve completion of mass ejection far from the disk. Comparing to viscous hydrodynamic simulations, we find that inclusion of magnetic fields result in a factor of two more mass ejected, at higher velocities, and with a wider electron fraction. Given our initial magnetic field geometry, we also obtain a powerful relativistic jet capable of powering a short gamma-ray burst and its non-thermal afterglow. |
Monday, April 15, 2019 11:33AM - 11:45AM |
Q16.00005: Status and prospects of the DES gravitational wave counterpart search and discovery pipeline Alyssa Garcia As proven from the detection of an electromagnetic counterpart to GW170817, time is of the essence when determining the counterpart to gravitational wave (GW) events. The Dark Energy Survey (DES) as well as many other groups will be searching for these counterparts during the next LIGO observing run (O3). In order to determine a host galaxy to such events quickly and efficiently, there are various steps needed. These steps, which include creating an observing plan, image processing, and curating a candidate list, create what we call the GW search pipeline. After the discovery of GW170817 we now expect an increased event rate and thus require improvements in our pipeline. We have achieved a factor of 5 improvement in data processing time and efficiency. In this talk I overview the status of our system and discuss the prospects for impactful science results during O3. |
Monday, April 15, 2019 11:45AM - 11:57AM |
Q16.00006: Searching for Prompt Radio Emission from Compact Binaries with the OVRO-LWA Thomas A Callister, Marin Anderson, Gregg Hallinan The multi-messenger observation of the binary neutron star merger GW170817 has yielded a wealth of astrophysical information, including the unambiguous observation of a kilonova and direct evidence for the association of short gamma-ray bursts and neutron star mergers. A still-missing piece of this puzzle, however, is the observation of a prompt low-frequency radio burst, which is predicted to accompany compact binary mergers mergers. The discovery of such a signal would be immensely valuable, but is made difficult by the very short delay between the gravitational-wave and radio signals as well as the poor localization of gravitational-wave sources. In this talk, I will describe efforts to detect prompt radio bursts associated with gravitational-wave events using the Owens Valley Radio Observatory’s Long Wavelength Array. I will present results from a proof-of-concept study targeting binary black holes in Advanced LIGO/Virgo’s O2 observing run and discuss plans to target binary neutron star mergers in the upcoming O3 run. |
Monday, April 15, 2019 11:57AM - 12:09PM |
Q16.00007: Gravitational-Wave Optical Counterpart Detection Methods for the TOROS Campaign During LVC O2 Observation Run Martin I Beroiz, Richard S Camuccio, Moises Castillo, Mario Claudio Diaz, Mariano J Dominguez, Marcelo Lares, Bruno Sanchez, Adam Zadrozny In this talk we will discuss the current status of optical transient (OT) detection on astronomical images taken by the TOROS Collaboration during the LVC Observation Run O2. We review several Difference Image Analysis methods and traditional Machine Learning techniques used to clean up recovered transient candidates, as well as new OT detection methods based on Convolutional Neural Networks and the use of raw pixels of the image. |
Monday, April 15, 2019 12:09PM - 12:21PM |
Q16.00008: Wide-survey difference imaging in the Dark Energy Survey Kenneth Herner, James Annis, Marcelle Soares-Santos
|
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700