Properties of the Binary Neutron Star Merger GW170817

Abstract

On August 17, 2017, the Advanced LIGO and Advanced Virgo gravitational-wave detectors observed a low-mass compact binary inspiral. The initial sky localization of the source of the gravitational-wave signal, GW170817, allowed electromagnetic observatories to identify NGC 4993 as the host galaxy. In this work, we improve initial estimates of the binary's properties, including component masses, spins, and tidal parameters, using the known source location, improved modeling, and recalibrated Virgo data. We extend the range of gravitational-wave frequencies considered down to 23 Hz, compared to 30 Hz in the initial analysis. We also compare results inferred using several signal models, which are more accurate and incorporate additional physical effects as compared to the initial analysis. We improve the localization of the gravitational-wave source to a 90% credible region of 16 deg 2 . We find tighter constraints on the masses, spins, and tidal parameters, and continue to find no evidence for nonzero component spins. The component masses are inferred to lie between 1.00 and 1.89 M ⊙ when allowing for large component spins, and to lie between 1.16 and 1.60 M ⊙ (with a total mass 2.73 þ0.04 −0.01 M ⊙ ) when the spins are restricted to be within the range observed in Galactic binary neutron stars. Using a precessing model and allowing for large component spins, we constrain the dimensionless spins of the components to be less than 0.50 for the primary and 0.61 for the secondary. Under minimal assumptions about the nature of the compact objects, our constraints for the tidal deformability parameterΛ are (0,630) when we allow for large component spins, and 300 þ420 −230 (using a 90% highest posterior density interval) when restricting the magnitude of the component spins, ruling out several equation-of-state models at the 90% credible level. Finally, with LIGO and GEO600 data, we use a Bayesian analysis to place upper limits on the amplitude and spectral energy density of a possible postmerger signal.

Updated parameter estimates for GW190425 using astrophysical arguments and implications for the electromagnetic counterpart

“…While none have a total mass of >2.9 M , there is a clear preference for equal-mass systems in this population. Additionally, the GW170817 BNS system and nearly all BBH systems are also consistent with their components having equal mass (Abbott et al 2019;The LIGO Scientific Collaboration et al 2018). It is clear that Nature produces many compact binary systems with near-equal mass.…”

Growth of Supermassive Black Hole Seeds in ETG Star-forming Progenitors: Multiple Merging of Stellar Compact Remnants via Gaseous Dynamical Friction and Gravitational-wave Emission

“…The overall event rate for the process of BH seed formation by gaseous dynamical friction considered here is generally higher by factors 3 − 10 than that for the merging of BH-BH binaries; however, one must caveat that the overall normalization of the latter curve is uncertain since it depends on several assumptions regarding complex processes of stellar astrophysics and binary evolution (e.g., binary fraction, common envelope development/survival, supernova kicks, mass transfers, etc. ), and has been actually set by comparison with the current AdvLIGO/Virgo measurements in the local Universe (see Abbott et al 2019;Boco et al 2019).…”

Наблюдение в гамма-диапазоне второго связанного со слиянием нейтронных звезд события LIGO/Virgo S190425z

“…For all 278 bursts of the sample selected in such a way, the background count rate of photons by the SPI-ACS detector was approximated by a polynomial of the 3rd degree in the intervals (T 0 −300 s, T 0 −50 s) and (T 0 +200 s, T 0 +500 s) -separately in each interval; the start time of the burst T 0 was taken from the catalog of the GBM monitor. The average value of two model count rates at 3 The persistenty updated catalog of bursts of this monitor can be found at the www-address heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html 4 Time interval between the moments of accumulation of 5% and 95% of the integrated number of counts by the GBM monitor (Koshut et al 1996).…”

“…Sensitivity of the detectors is growing rapidly: there were only 3 events recorded in the O1 cycle of the LIGO work (since September 12, 2015 till January 19, 2016), 8 events recorded in the O2 cycle (since November 23, 2016 till August 25, 2017), and already 31 events recorded in O3 (started on April 1, 2019) by the end of September 2019. The catalog of events for cycles O1-O2 can be found in Abbott et al (2019), the current list of O3 events -on the web-site gracedb.ligo.org/superevents/public/O3. * e-mail: apozanen@iki.rssi.ru…”