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Astrophysics, High Energy Astrophysical Phenomena, astro-ph.HE,General Relativity and Quantum Cosmology, gr-qc
Abstract:
On 2019 April 25, the LIGO Livingston detector observed a compact binary
coalescence with signal-to-noise ratio 12.9. The Virgo detector was also taking
data that did not contribute to detection due to a low signal-to-noise ratio,
but were used for subsequent parameter estimation. The 90% credible intervals
for the component masses range from 1.12 to 2.52 $M_{\odot}$ (1.45 to 1.88
$M_{\odot}$ if we restrict the dimensionless component spin magnitudes to be
smaller than 0.05). These mass parameters are consistent with the individual
binary components being neutron stars. However, both the source-frame chirp
mass $1.44^{+0.02}_{-0.02} M_{\odot}$ and the total mass
$3.4^{+0.3}_{-0.1}\,M_{\odot}$ of this system are significantly larger than
those of any other known binary neutron star system. The possibility that one
or both binary components of the system are black holes cannot be ruled out
from gravitational-wave data. We discuss possible origins of the system based
on its inconsistency with the known Galactic binary neutron star population.
Under the assumption that the signal was produced by a binary neutron star
coalescence, the local rate of neutron star mergers is updated to $250-2810
\text{Gpc}^{-3}\text{yr}^{-1}$.