Characterization of merging black holes with two precessing spins
Abstract
Spin precession in merging blackhole binaries is a treasure trove for both astrophysics and fundamental physics. There are now wellestablished strategies to infer from gravitationalwave data whether at least one of the two black holes is precessing. In this paper we tackle the nextinline target, namely the statistical assessment that the observed system has two precessing spins. We find that the recently developed generalization of the effective precession spin parameter χ_{p} is a wellsuited estimator to this task. With this estimator, the occurrence of two precessing spins is a necessary (though not sufficient) condition to obtain values 1 <χ_{p}≤2 . Confident measurements of gravitationalwave sources with χ_{p} values in this range can be taken as a conservative assessment that the binary presents two precessing spins. We investigate this argument using a large set of >100 software injections assuming anticipated LIGO/Virgo sensitivities for the upcoming fourth observing run, O4. Our results are very encouraging, suggesting that, if such binaries exist in nature and merge at a sufficient rate, current interferometers are likely to deliver the first confident detection of merging black holes with two precessing spins. We investigate prior effects and waveform systematics and, though these need to be better investigated, did not find any confident falsepositive case among all the configurations we tested. Our assessment should thus be taken as conservative.
 Publication:

Physical Review D
 Pub Date:
 October 2022
 DOI:
 10.1103/PhysRevD.106.084040
 arXiv:
 arXiv:2207.00030
 Bibcode:
 2022PhRvD.106h4040D
 Keywords:

 General Relativity and Quantum Cosmology;
 Astrophysics  High Energy Astrophysical Phenomena
 EPrint:
 12 pages, 8 figures, 1 table