TY - JOUR

T1 - On the Single-event-based Identification of Primordial Black Hole Mergers at Cosmological Distances

AU - Ng, Ken K.Y.

AU - Chen, Shiqi

AU - Goncharov, Boris

AU - Dupletsa, Ulyana

AU - Borhanian, Ssohrab

AU - Branchesi, Marica

AU - Harms, Jan

AU - Maggiore, Michele

AU - Sathyaprakash, B. S.

AU - Vitale, Salvatore

N1 - Publisher Copyright:
© 2022. The Author(s). Published by the American Astronomical Society.

PY - 2022/5/1

Y1 - 2022/5/1

N2 - The existence of primordial black holes (PBHs), which may form from the collapse of matter overdensities shortly after the Big Bang, is still under debate. Among the potential signatures of PBHs are gravitational waves (GWs) emitted from binary black hole (BBH) mergers at redshifts z 3 30, where the formation of astrophysical black holes is unlikely. Future ground-based GW detectors, the Cosmic Explorer and Einstein Telescope, will be able to observe equal-mass BBH mergers with total mass of (10-100)M⊙ at such distances. In this work, we investigate whether the redshift measurement of a single BBH source can be precise enough to establish its primordial origin. We simulate BBHs of different masses, mass ratios and orbital orientations. We show that for BBHs with total masses between 20 M ⊙ and 40 M ⊙ merging at z ≥ 40, one can infer z > 30 at up to 97% credibility, with a network of one Einstein Telescope, one 40 km Cosmic Explorer in the US, and one 20 km Cosmic Explorer in Australia. This number reduces to 94% with a smaller network made of one Einstein Telescope and one 40 km Cosmic Explorer in the US. We also analyze how the measurement depends on the Bayesian priors used in the analysis and verify that priors that strongly favor the wrong model yield smaller Bayesian evidences.

AB - The existence of primordial black holes (PBHs), which may form from the collapse of matter overdensities shortly after the Big Bang, is still under debate. Among the potential signatures of PBHs are gravitational waves (GWs) emitted from binary black hole (BBH) mergers at redshifts z 3 30, where the formation of astrophysical black holes is unlikely. Future ground-based GW detectors, the Cosmic Explorer and Einstein Telescope, will be able to observe equal-mass BBH mergers with total mass of (10-100)M⊙ at such distances. In this work, we investigate whether the redshift measurement of a single BBH source can be precise enough to establish its primordial origin. We simulate BBHs of different masses, mass ratios and orbital orientations. We show that for BBHs with total masses between 20 M ⊙ and 40 M ⊙ merging at z ≥ 40, one can infer z > 30 at up to 97% credibility, with a network of one Einstein Telescope, one 40 km Cosmic Explorer in the US, and one 20 km Cosmic Explorer in Australia. This number reduces to 94% with a smaller network made of one Einstein Telescope and one 40 km Cosmic Explorer in the US. We also analyze how the measurement depends on the Bayesian priors used in the analysis and verify that priors that strongly favor the wrong model yield smaller Bayesian evidences.

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U2 - 10.3847/2041-8213/ac6bea

DO - 10.3847/2041-8213/ac6bea

M3 - Article

AN - SCOPUS:85130996021

SN - 2041-8205

VL - 931

JO - Astrophysical Journal Letters

JF - Astrophysical Journal Letters

IS - 1

M1 - L12

ER -