New binary black hole mergers in the LIGO--Virgo O3a data

Abstract

We report the detection of ten new binary black hole (BBH) merger signals in the publicly released data from the the first half of the third observing run (O3a) of advanced LIGO and advanced Virgo. Candidates are identified using an updated version of the search pipeline described in Venumadhav et al.[1] (the "IAS pipeline" [2]), and events are declared according to criteria similar to those in the GWTC-2.1 catalog [3]. The updated search is sensitive to a larger region of parameter space, applies a template prior that accounts for different search volume as a function of intrinsic parameters, and uses an improved coherent detection statistic that optimally combines the data from the Hanford and Livingston detectors. Among the ten new events, we observe interesting astrophysical scenarios including sources with confidently large effective spin parameters in both the positive and negative directions, high-mass black holes that are difficult to form in stellar collapse models due to (pulsational) pair instability, and low-mass mergers that bridge the gap between neutron stars and the lightest observed black holes. We detect events populating the upper and lower black hole mass gaps with both extreme and near-unity mass ratios, and one of the possible neutron star-black hole (NSBH) mergers is well localized for electromagnetic (EM) counterpart searches. We see a substantial increase in significance for many of the events previously reported by other pipelines, and we detect all of the GWTC-2.1 BBH mergers with coincident data in Hanford and Livingston except for three loud events that get vetoed, which is compatible with the falsepositive rate of our veto procedure, and three that fall below the detection threshold. We also return to significance the event GW190909 114149, which was reduced to a sub-threshold trigger after its initial appearance in . This amounts to a total of 42 BBH mergers detected by our pipeline's search of the coincident Hanford-Livingston O3a data.

A Channel to Form Fast-spinning Black Hole--Neutron Star Binary Mergers as Multi-messenger Sources

“…Very recently, Olsen et al (2022) reported an marginal candidate, GW190920 113516, whose secondary could be a heavy NS. With an effective inspiral spin of χ eff = 0.60 +0.26 −0.07 , this event could be a potential NSBH merger with the NS first born.…”

Spectral sirens: cosmology from the full mass distribution of compact binaries

“…We focus on the findings from LVK. Independent groups have reproduced these results and found additional events[48][49][50].…”

Broad search for gravitational waves from subsolar-mass binaries through LIGO and Virgo's third observing run

“…Gravitational waves are now regularly observed by the ground-based observatories Advanced LIGO [1] and Advanced Virgo [2]. Their accomplishments include more than 90 observed binary black hole (BBH) mergers [3][4][5] and a handful of binary neutron star [6,7] and neutron star -black hole mergers [8]. These observations provide a wealth of knowledge for understanding the population of stellar-mass black holes [9], which may have arisen through standard stellar evolution [10].…”