Search for intermediate mass black hole binaries in the third observing run of Advanced LIGO and Advanced Virgo

Abstract

Intermediate-mass black holes (IMBHs) span the approximate mass range 100-10 5 M , between black holes (BHs) formed by stellar collapse and the supermassive BHs at the centers of galaxies. Mergers of IMBH binaries are the most energetic gravitational-wave sources accessible by the terrestrial detector network. Searches of the first two observing runs of Advanced LIGO and Advanced Virgo did not yield any significant IMBH binary signals. In the third observing run (O3), the increased network sensitivity enabled the detection of GW190521, a signal consistent with a binary merger of mass ∼ 150 M providing direct evidence of IMBH formation.Here we report on a dedicated search of O3 data for further IMBH binary mergers, combining both modelled (matched filter) and model independent search methods. We find some marginal candidates, but none are sufficiently significant to indicate detection of further IMBH mergers. We quantify the sensitivity of the individual search methods and of the combined search using a suite of IMBH binary signals obtained via numerical relativity, including the effects of spins misaligned with the binary orbital axis, and present the resulting upper limits on astrophysical merger rates. Our most stringent limit is for equal mass and aligned spin BH binary of total mass 200M and effective aligned spin 0.8 at 0.056 Gpc −3 yr −1 (90% confidence), a factor of 3.5 more constraining than previous LIGO-Virgo limits. We also update the estimated rate of mergers similar to GW190521 to 0.08 Gpc −3 yr −1 .

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

“…Interestingly, the evidence of i) is roughly consistent with the theory of PISN and its prediction for a mass gap, known as the PISN gap or upper mass gap. Since current sensitivities drop above the upper edge of the PISN gap, we are still agnostic about a possible population of far-side binaries above this feature [37], although we have upper bounds on their rate [45]. On the other hand, ii) would be consistent with electromagnetic observations suggesting a NSBH gap or lower mass gap [52][53][54].…”

Salient features of the optimised PyCBC IMBH search

“…We also compare our search against two other searches, namely cWB and GstLAL-IMBH, that were used by the LIGO Scientific, Virgo & Kagra collaboration (LVK) to look for IMBH binaries in O3 run [15]. For this purpose, we utilise the results of the injection campaign that were used by the LVK to place Table 1.…”

“…The signals themselves were numerically simulated and are designed to imitate GWs from a representative population of IMBH binaries with generic spins. Additional details about the injections can be found in [15].…”

“…To estimate V T using the publicly available dataset, we start off by calculating the number of signals that are recovered by each of three contributing searches. We do this by considering only those injections whose p-value is less than the minimum p-value of the loudest noise trigger, namely that of 200214 224526 in the [15]. This trigger has a minimum p-value of 9.2 × 10 −2 and was only reported by the weakly model-dependent cWB search.…”

“…Here, we will summarise the salient features of one of the optimised templated searches, namely PyCBC-IMBH that was developed and deployed for the IMBH binary search. This optimised search was used together with other search pipelines to look for IMBH binaries in the O3 run, and the reader can find the results of it in [15]. For complete information on the algorithm itself, we direct the reader to the optimised PyCBC IMBH search paper [16].…”