Bulletin of the American Physical Society
APS April Meeting 2019
Volume 64, Number 3
Saturday–Tuesday, April 13–16, 2019; Denver, Colorado
Session T16: Gravitational Wave Signal Searches |
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Sponsoring Units: DGRAV Chair: Maura McLaughlin, West Virginia University Room: Sheraton Grand Ballroom I |
Monday, April 15, 2019 3:30PM - 3:42PM |
T16.00001: Results from the search for a stochastic gravitational wave background in the NANOGrav 12.5-year data set Joseph Simon Pulsar timing arrays are galactic-scale low-frequency gravitational wave observatories sensitive to the nanohertz frequency band. The primary source of gravitational radiation in this regime is expected to be a stochastic background, formed by a cosmic population of supermassive black hole binaries. We present the results obtained by analyzing the 12.5-year data release from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) including constraints on the putative source population. We also discuss advanced noise modeling techniques for individual millisecond pulsars in the NANOGrav dataset, which has improved our sensitivity. |
Monday, April 15, 2019 3:42PM - 3:54PM |
T16.00002: Sub-threshold binary neutron star search in Advanced LIGO's first observing run RYAN MAGEE We present a search for gravitational waves from binary neutron stars in Advanced LIGOs first observing run using data publicly available via the Gravitational Wave Open Science Center (GWOSC). We consider a narrow range of binary chirp masses motivated by the population of known double neutron star binaries in the local universe. The analysis includes times when only one of the two LIGO interferometers was in operation; this is the first search to assign significances to candidates found in single detector time. No individually unambiguous gravitational wave candidates were identified in our sample of 103 sub-threshold candidates with false-alarm-rates of less than one per day. From the expected binary neutron star merger rate, we infer that O(1) of these sub-threshold candidates is in fact a binary neutron star merger. It could be possible to correlate these candidates with other astrophysical messengers to identify a potential multi-messenger signal. We provide an online catalog of the times and sky locations for each sub-threshold candidate to enable multi-messenger follow up. |
Monday, April 15, 2019 3:54PM - 4:06PM |
T16.00003: Results from the Intermediate-Mass Black Hole Search in Advanced LIGO Karan P Jani The Advanced LIGO detectors can survey the population of intermediate-mass black hole mergers further than any known gravitational wave source. This talk highlights our findings from the search for the intermediate-mass black holes during the first and second observing runs of Advanced LIGO detectors (2015-2017). We discuss our primary results and their astrophysical implications. These results also mark the first direct application of numerical relativity waveforms for making rate measurements in real Advanced era data. |
Monday, April 15, 2019 4:06PM - 4:18PM |
T16.00004: Searches for sub-solar mass ultracompact objects with Advanced LIGO Phoebe K McClincy Advanced LIGO and Advanced Virgo have revealed a rich population of binary black holes and neutron stars, and this has revived interest in the possibility of sub-solar mass ultracompact objects. Since astrophysical processes are not expected to produce ultracompact objects below one solar mass, the detection of a sub-solar mass ultracompact object could therefore be an indication of primordial black holes. It has been proposed that low mass black holes could be formed primordially through density fluctuations in the early Universe and contribute to the dark matter density. We present results for the first Advanced LIGO searches for sub-solar mass ultracompact objects, as well as an interpretation of these results in the context of primordial black holes as a component of dark matter. |
Monday, April 15, 2019 4:18PM - 4:30PM |
T16.00005: Directed searches for gravitational waves from ultralight bosons Maximiliano Isi, Ling Sun, Richard Brito, Andrew Melatos Black-hole superradiance may make it possible to detect or constrain yet-undiscovered ultralight bosons using gravitational waves. In this talk, I will describe how we may achieve this with ground-based detectors by searching for continuous gravitational waves from known black holes. This includes black holes in x-ray binaries and remnants from compact-binary mergers. I will present results from the recovery of simulated signals from noisy data using hidden Markov models. This efficient data analysis technique will make it possible to target remnants from compact-binary mergers localized with at least three instruments like LIGO and Virgo. I will present sensitivity projections for 2G and 3G ground-based detectors and, in closing, discuss specific potential targets and their associated challenges. |
Monday, April 15, 2019 4:30PM - 4:42PM |
T16.00006: Loosely coherent searches for continuous waves Vladimir Dergachev Continuous waves from non-axisymmetric neutron stars are orders of magnitude weaker than transient events from black hole and neutron star collisions. |
Monday, April 15, 2019 4:42PM - 4:54PM |
T16.00007: Memory Detection Prospects for Low-Frequency Gravitational Wave Detectors Kristina Islo General Relativity predicts the gravitational wave signature from coalescing compact binaries to be accompanied by a non-periodic signal born of the non-linearities in Einstein's field equations. This effect is deemed "memory" as it accumulates from the entire past emission of the system. During the most dynamic stages of binary merger, the memory exponentially increases until the masses are tidally disrupted, at which point the signal saturates to a constant value. This effect propagates out into the ambient space, permanently deforming all it encounters. Supermassive system coalescences emit memory signals with amplitudes detectable by low-frequency gravitational wave detectors, including pulsar timing arrays (PTAs) and the Laser Interferometer Space Antenna (LISA). A detection would allow strong-field tests of General Relativity, provide an alternate method for observing binary coalescence, and place constraints on their formation. In this talk I present current PTA sensitivity to this effect from a simulated population of coalescing supermassive black hole binaries, and estimate LISA's ability to witness memory from these same systems. |
Monday, April 15, 2019 4:54PM - 5:06PM |
T16.00008: An Unmodelled Bayesian Burst Search for Gravitational Waves Atul Divakarla, Eric Thrane, Paul Lasky, Bernard F Whiting The nonlinear memory effect is a theoretical consequence of General Relativity, first brought to attention by Demetrios Christodoulou in 1991 and later elaborated on by Kip Thorne in 1992. It is understood that there exists a low-frequency memory component, for all gravitational wave bursts, that is of the same order of magnitude as the original oscillatory burst but of different spectral content. Orphan memory is defined as a memory signal for which there is no detectable oscillatory counterpart. By making use of the novel parameter estimation software `Bilby', we provide the first unmodelled burst search method for recovering an orphan memory signal's phenomenological parameters using parameter estimation with Bayesian inference. We show that, if a memory-like signal does exist within LIGO's data, then our analysis has the full capability of detecting it with statistical significance. For future projects we plan to generalize and implement this as a pipeline for the low-frequency memory component, falling within LIGO's sensitivity bandwidth, arising from unmodelled high-frequency gravitational wave bursts, such as from cosmic strings interactions. |
Monday, April 15, 2019 5:06PM - 5:18PM |
T16.00009: Detecting non-GR polarization states of continuous gravitational waves with pulsar timing arrays Logan T O'Beirne, Neil J Cornish, Stephen R Taylor, Sarah J Vigeland Pulsar timing arrays are sensitive to resolvable supermassive black hole binaries in the very early inspiral phase. Modified gravity theories allow for the emission of gravitational dipole radiation, which appears at -1 post-Newtonian order relative to the leading GR contribution, making the very early inspiral an opportune regime to test for the presence of modified gravity effects. Using a theory-agnostic generalization of modified gravity theories based on the parametrized post-Einsteinian framework, we explore the efficiency of detecting non-GR polarization strains with simulated pulsar timing array data, and subsequently find their upper limits as a function of sky location. |
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