Bulletin of the American Physical Society
APS April Meeting 2018
Volume 63, Number 4
Saturday–Tuesday, April 14–17, 2018; Columbus, Ohio
Session U13: Gravitational Waves: Source Modeling - III |
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Sponsoring Units: DGRAV Chair: Jocelyn Read, Cal State Fullerton Room: A224-225 |
Monday, April 16, 2018 3:30PM - 3:42PM |
U13.00001: GW170817: Joint Constraint on the Neutron Star Equation of State from Gravitational Waves and Electromagnetic Observations David Radice, Albino Perego, Francesco Zappa, Bernuzzi Sebastiano Gravitational wave data for the binary neutron star merger event GW170817 constrained the neutron star equation of state by placing an upper bound on certain parameters describing the binary's tidal interactions. In my talk, I will show that using new numerical relativity simulations it is possible to infer a complementary lower bound on the tidal deformability parameter using the UV/optical/infrared counterpart of GW170817. The joint constraints tentatively rule out both extremely stiff and soft neutron star equations of state. [Preview Abstract] |
Monday, April 16, 2018 3:42PM - 3:54PM |
U13.00002: Recovering the Neutron Star Equation of State from a Binary Neutron Star Gravitational Wave Detection with LIGO Matthew Carney, Burke Irwin, Leslie Wade During the collision of two orbiting neutron stars, the gravitational gradient across one due to the other causes tidal deformations in the neutron star. This deformation causes a change in quadrupole moment of the binary system, which in turn alters the gravitational waveform emitted during the inspiral and eventual collision of the two neutron stars. Such an alteration of the gravitational waveform can give us insight into the behavior and structure of neutron star matter in the form of constraints on the neutron-star equation of state (EOS). We can generate waveforms that include alterations due to tidal deformations and use parameter estimation techniques to measure the model parameters and constrain the equation of state in general. Recent work has involved incorporating a new EOS model into LIGO's fully Bayesian parameter estimation routines and is currently being tested to determine the effectiveness of this method of EOS measurement on a simulated population of neutron star gravitational-wave signals. With LIGO's first binary neutron star detection, GW170817, and potentially more on the way, we can use these methods to directly measure the true neutron star equation of state. [Preview Abstract] |
Monday, April 16, 2018 3:54PM - 4:06PM |
U13.00003: Inferring the post-merger gravitational wave emission from binary neutron star coalescences Margaret Millhouse, Katerina Chatziioannou, James Clark, Andreas Bauswein, Tyson Littenberg, Neil Cornish Gravitational-wave signals from coalescing neutron stars can provide a wealth of information about neutron star interiors. The first detection of such an event was recently announced by Advanced LIGO. This indicates that in future observing runs we can expect to see more neutron star mergers, giving us the opportunity to observe a signal from the merger remnant. Gravitational-wave emission from this post-merger phase is dominated by the complex dynamics of the merger and highly sensitive to the neutron star equation of state, making precise analytic waveform models unfeasible at this time. For this reason it is important to have the ability to reconstruct these post-merger signals with minimal prior assumptions on the morphology of the signal for both the detection and characterization of this signal, and to observationally validate future waveform models. We present a robust technique to characterize the post-merger burst of gravitational-waves from remnants of binary neutron star mergers. We show how our model-agnostic reconstructions can be used to constrain the equation of state of neutron star matter that are comparable to constraints from the pre-merger phase, and how we can measure or place upper limits on the amount of energy emitted as gravitational waves after merger. [Preview Abstract] |
Monday, April 16, 2018 4:06PM - 4:18PM |
U13.00004: Gravitational wave spectroscopy of binary neutron star merger remnants with mode stacking Huan Yang, Vasileios Paschalidis, Kent Yagi, Luis Lehner, Frans Pretorius, Nicolas Yunes A binary neutron star merger event has recently been observed for the first time in gravitational waves, and many more detections are expected in the near future. The post-merger signal, however, can only be expected to be measurable by current detectors for events closer than roughly 10 Mpcs, which given merger rate estimates implies a low probability of observation within the expected lifetime of these detectors. We carry out Monte-Carlo simulations to investigate the chance of detecting that the dominant post-merger mode from individual binary neutron star mergers. To boost the post-merger detection probability, we propose two methods that stack the post-merger signal from multiple binary neutron star observations. The first method follows a commonly-used practice of multiplying the Bayes factors of individual events. The second method relies on an assumption that the mode phase can be determined from the inspiral waveform, so that coherent mode stacking of the data from different events becomes possible. We find that both methods significantly improve the chances of detecting the dominant post-merger signal, making a detection very likely after a year of observation using third-generation detectors (e.g., Cosmic Explorer). [Preview Abstract] |
Monday, April 16, 2018 4:18PM - 4:30PM |
U13.00005: Placing Constraints on a Neutron Star Equation of State using Heirarchical Population Inference Monica Rizzo, Richard O'Shaughnessy With the recent detection of gravitational waves from binary neutron stars (BNSs), it has become crucial to understand and optimize methods of recovering information from these types of events. BNS mergers convey a wealth of information, including clues as to what the nuclear equation of state (EOS) of cold high density matter might be. In order to recover information about the composition of neutron stars with minimal bias, we assume a direct relationship between their mass and tidal deformability ($\lambda$) - unique to EOSs - when estimating their parameters using Bayesian techniques. We then implement a spectral EOS parameterization method (Lindblom 2010), where each EOS is described by 4 free variables. Then, for a population of realistic BNS events, we use Bayesian hierarchical parameter estimation to recover these EOS parameters. The inferences made can potentially be used to probe fundamental physics and place bounds on a plausible nuclear EOS. [Preview Abstract] |
Monday, April 16, 2018 4:30PM - 4:42PM |
U13.00006: Constraining the nuclear equation of state with multiple observational channels Richard O'Shaughnessy, Jocelyn Read, Monica Rizzo, Andrew Steiner, Les Wade, Daniel Wysocki In the next few years, both gravitational wave observations and X-ray timing observations will provide complementary ways to measure the nuclear equation of state. Projecting forward to the future based on plausible astrophysical populations and measurement opportunities available in the next few years, we show that multi-messenger and multi-object observations will allow us to constrain the nuclear equation of state to O(30\%) just above the nuclear saturation density. [Preview Abstract] |
Monday, April 16, 2018 4:42PM - 4:54PM |
U13.00007: Observing universal tidal relations in neutron star binaries Carl-Johan Haster, Katerina Chatziioannou, Aaron Zimmerman, Kent Yagi The tidal deformability of neutron stars holds precious information about matter at the most extreme scales, including the still unknown neutron star equation of state. In this talk, I'll show that by assuming a universal relation between the tidal deformabilities of the two neutron stars in a binary, and accounting for the uncertainty present in such a relation, one will arrive at a physically motivated measure of the tidal deformabilities of the neutron stars through observations of gravitational waves emitted from such systems. Compared to other approaches these deformabilities will be well constrained, and through the use of the universal relation this method will be applicable to all neutron star equations of state. [Preview Abstract] |
Monday, April 16, 2018 4:54PM - 5:06PM |
U13.00008: Combining information from multiple gravitational wave signals Katerina Chatziioannou, Carl-Johan Haster, Aaron Zimmerman Gravitational waves can be used to characterize the properties of their sources, with many subtle effects -such as deviation from general relativity- more effectively studied by combining information from many such signals. In this talk I will describe the assumptions implicit in various methods for combining information from multiple sources and discuss their implications. I will show that the correlations between the parameters of interest need to be taken into account, as they affect how rapidly information is accumulated. [Preview Abstract] |
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