GW190425: Observation of a Compact Binary Coalescence with Total Mass ∼ 3.4 M_⊙

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 to ( – 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 and the total mass of this system are significantly larger than those of any other known binary neutron star (BNS) 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 BNS population. Under the assumption that the signal was produced by a BNS coalescence, the local rate of neutron star mergers is updated to 250–2810 .

Common envelope episodes that lead to double neutron star formation

“…The merger rate of DNSs was inferred to fall in the range 110-3840 Gpc 3 /yr with 90% confidence (Abbott et al 2019) based on a single detection of GW170817 with a flat-in-rate prior (Abbott et al 2017). The detection of GW190425 under the assumption of a DNS progenitor updates the local DNS merger rate to 250-2810 Gpc 3 /yr (Abbott et al 2020).…”

O3 highlights

“…It was another neutron star merger, but no electromagnetic counter part was found. The combined mass of this binary sys tem (about 3.4 solar masses) is much larger than was expected from the known galactic neutron star bina ries 4 . Interestingly, the event was detected only by the Livingston interferometer, because the Hanford detector was temporarily offline at the time and the Virgo data had a low signal to noise ratio.…”

Gravity in the infrared and effective nonlocal models

“…Furthermore, the event was near a blind spot of Virgo, so Virgo could contribute to the source localization but not to the estimate of the other source parameters, so only the two LIGO detectors contributed to the estimate of dL. 40 The recently announced detection, GW190425 [217], has a redshift z = 0.03 +0.01 −0.02 (assuming ΛCDM). The event is classified as a NS-NS, although the possibility that one or both binary components of the system are BHs cannot be ruled out from the GW data.…”