Abstract
Abstract We report the observation of a compact binary coalescence involving a 22.2–24.3 M ⊙ black hole and a compact object with a mass of 2.50–2.67 M ⊙ (all measurements quoted at the 90% credible level). The gravitational-wave signal, GW190814, was observed during LIGO’s and Virgo’s third observing run on 2019 August 14 at 21:10:39 UTC and has a signal-to-noise ratio of 25 in the three-detector network. The source was localized to 18.5 deg2 at a distance of Mpc; no electromagnetic counterpart has been confirmed to date. The source has the most unequal mass ratio yet measured with gravitational waves, , and its secondary component is either the lightest black hole or the heaviest neutron star ever discovered in a double compact-object system. The dimensionless spin of the primary black hole is tightly constrained to ≤0.07. Tests of general relativity reveal no measurable deviations from the theory, and its prediction of higher-multipole emission is confirmed at high confidence. We estimate a merger rate density of 1–23 Gpc−3 yr−1 for the new class of binary coalescence sources that GW190814 represents. Astrophysical models predict that binaries with mass ratios similar to this event can form through several channels, but are unlikely to have formed in globular clusters. However, the combination of mass ratio, component masses, and the inferred merger rate for this event challenges all current models of the formation and mass distribution of compact-object binaries.
Highlights
The first two observing runs (O1 and O2) with Advanced LIGO (Aasi et al 2015) and Advanced Virgo
The results indicate that the inferred secondary mass is robust to possible waveform systematics, with good agreement between the Phenom PHM and EOBNR PHM signal models
We find a minimum p–value of 6.8 × 10−3 at α = 1.5, providing strong evidence that the disagreement between the actual event and the EOBNR prediction is because of the absence of the m = 3 multipoles in the waveform model
Summary
The first two observing runs (O1 and O2) with Advanced LIGO (Aasi et al 2015) and Advanced Virgo As in the case of GW190412, we are able to measure the presence of higher multipoles in the gravitational radiation, and a set of tests of general relativity with the signal reveal no deviations from the theory Treating this event as a new class of compact binary coalescences, we estimate a merger rate density of 1–23 Gpc−3 yr−1 for GW190814-like events. Thunderstorms near LIGO Livingston around the time of GW190814 resulted in acoustic noise coupling to the detector and caused features in the strain data associated with scattered light (Abbott et al 2019a) In this instance, this form of noise affects frequencies up to 30 Hz from roughly 22 s to 8 s before and 0.2 s to 1.5 s after the detected time of GW190814, as seen in the middle panel of Figure 1. These calibration uncertainties are propagated into the parameter estimation reported in Section 4 via marginalization
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