Bulletin of the American Physical Society
APS April Meeting 2019
Volume 64, Number 3
Saturday–Tuesday, April 13–16, 2019; Denver, Colorado
Session R16: Compact Binary Formation Channels and Dynamics |
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Sponsoring Units: DAP DGRAV Chair: Zoheyr Doctor, University of Chicago Room: Sheraton Grand Ballroom I |
Monday, April 15, 2019 1:30PM - 1:42PM |
R16.00001: Binary Black Hole Population Properties Inferred from the First and Second Observing Runs of Advanced LIGO and Advanced Virgo Chris Pankow The first two observing runs of the LIGO/Virgo gravitational-wave interferometer network have produced ten binary black holes as well as the historic detection of a binary neutron star. In this talk, I will show how the binary black hole properties measured from those detections are shaping our understanding of black hole populations. Through parameterized modelling of the mass, spin, and redshift distributions inferred from the events in those runs, several features are becoming apparent. Namely, binary mergers with masses above 45 solar masses must be comparatively rare, fast black hole spins which are aligned with the binary orbital angular momentum are disfavored, and there is preference against declining evolution of merger rate with redshift. |
Monday, April 15, 2019 1:42PM - 1:54PM |
R16.00002: Inferring Binary-Black-Hole Formation Channels in Third-Generation Gravitational-Wave Detectors Ken K. Y. Ng, Salvatore Vitale, Will Meierjurgen Farr, Carl Rodriguez Future gravitational-wave (GW) detector-network will detect binary-black-hole mergers (BBHs) up to redshift of ~10, which provides a direct measurement of the formation history of BBHs. Here we show how GW detections of BBHs made by proposed third-generation detectors can be used to infer the formation channels of BBHs. To distinguish between the two main expected formation channels-- dynamical formation or binary stellar evolution--we parametrize the redshift distribution predicted by cosmological simulation in each channel and infer their branching ratio and characteristic parameters. With one month of observations at the predicted rate of ~15000 BBHs per month, parameters describing the volumetric merger rate can be constrained at the few percent level. |
Monday, April 15, 2019 1:54PM - 2:06PM |
R16.00003: Double Neutron-Star Formation from Supernova Natal Kicks A. Miguel Holgado, Paul Milton Ricker A neutron star emerging from the common-envelope phase may be paired with a helium-star companion. The helium star may eventually undergo a supernova explosion and form a double neutron-star system. Compact-binary population-synthesis codes often treat the transition from the pre-supernova to the post-supernova state as an instantaneous process. We investigate this phase transition with a more sophisticated model that accounts for the finite timescales of the supernova mass loss and natal kick. We compare how treating the finite timescales affects the final orbital characteristics of double neutron star populations with those predicted from the prescriptions often used in binary population-synthesis codes. |
Monday, April 15, 2019 2:06PM - 2:18PM |
R16.00004: Relativistic Dynamics in Black Hole Triples Halston Lim, Carl Rodriguez Binary black holes can be driven to merger by interactions with a third companion via the Lidov-Kozai mechanism. The impact of this mechanism may be observable by LIGO/Virgo through the production of binaries with distinct eccentricity. We present a direct method to derive the orbit averaged gravitational dynamics of a hierarchical three-body system to first post-Newtonian order. We start with the Einstein-Infeld-Hoffman (EIH) equations for a three-body system and write the accelerations as a power series in the ratio of the semi-major axes of the two orbits, (a1/a2). At zeroth order, the two orbits evolve independently. At first order, orbital interaction terms (of both Newtonian and relativistic nature) start to appear, and sub-leading interaction terms appear at higher powers in (v/c) and (a1/a2). These interaction terms become important when the three-body Newtonian timescales are comparable to the relativistic timescales and provide an analytic description of behavior observed in previous N-body simulations. |
Monday, April 15, 2019 2:18PM - 2:30PM |
R16.00005: Spin misalignments of binary black holes produced in the isolated field channel Michael Kesden, Nathan A Steinle We explore how the stellar evolution of binary black hole (BBH) progenitors determines the spin misalignments and precessional morphologies of BBHs near merger. Relevant aspects of stellar evolution include: (1) common envelope evolution, which brings the BBHs close enough together to merge through gravitational-wave emission, (2) stable mass transfer, which can reverse the mass ratio of the stellar progenitors and favor one librating morphology over another, (3) natal kicks which can source BBH misalignments even for initially aligned stellar progenitors, (4) tides which can align progenitors spin with their orbital angular momentum and synchronize the orbital and rotational angular velocities, and (5) stellar winds which can reduce the progenitor spins. We examine how the competing influences of these processes depend on the initial masses, spins, metallicities, and binary separations of the BBH progenitors and identify the portions of parameter space most likely to be associated with distinctive BBH spin precession when the BBHs enter the sensitivity band of gravitational-wave detectors. This research will help to interpret future discoveries of precessing BBHs. |
Monday, April 15, 2019 2:30PM - 2:42PM |
R16.00006: Non-Parametric Population Models of Gravitational Waves Zoheyr Doctor I will describe techniques for finding structure in LIGO and Virgo data and for modeling the populations of black hole binaries. |
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