{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"2ee072e97b13fb6e48cda8712247d04c5a03bfd871608e8c658c3319ac478b0d","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b","de6054bbd1a6195f2e031d87c4a4de1915b78c639a4f90d48d3e74df18b83db4"],"salt":"2803d0f2c4fff2016363fa4bb0d7bc1c56b1565aa2d87fa0ebd0b93217ea996a","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"cosmo.primordial-black-holes.merger-fraction","kind":"well-posed","literature_status":"open","n":"2","parents":[],"plain":"Gravitational-wave detectors have recorded hundreds of colliding black holes. Some of them might have been born in the early universe instead of from dying stars.","posed_since":"2016","precise":"Determine the fraction of the LIGO-Virgo-KAGRA binary black hole merger rate contributed by primordial black holes, or an upper bound on it, using mass, spin and redshift distributions. A sub-solar-mass black hole ($M < 1\\,M_{\\mathrm{sun}}$) in a merger would strongly favor primordial origin, since stellar collapse cannot make black holes below about $1\\,M_{\\mathrm{sun}}$ (the remaining alternative being neutron stars converted to black holes by captured dark matter); mergers at redshift $z > 30$ seen by third-generation detectors would also point to primordial origin.","problem_ref":"de6054bbd1a6195f2e031d87c4a4de1915b78c639a4f90d48d3e74df18b83db4","references":"","settled_by":"Detection or exclusion of sub-solar-mass compact binary mergers, plus redshift-resolved merger rates from Einstein Telescope or Cosmic Explorer.","status_note":"Mroz et al. (2024) bound compact halo objects of $1.8 \\times 10^{-4} \\text{ to } 6.3\\,M_{\\mathrm{sun}}$ below 1 percent of dark matter; the O4 candidate S251112cm (2025), found by the sub-solar-mass search, has low significance (false-alarm rate about 1 per 6 yr), and no confident sub-solar-mass merger exists.","title":"Do any observed black-hole mergers involve primordial black holes?","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"83b195ca4da1af80803a849c9333512657331a8fd5d31578a1524993b5054192","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"fb47249b08c96c2625392307910832ec229db2f754a7f3244d7ae0443682b338","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"z_nVu3pNE7pdTFUFqEyov8jVgIzI2iXABcyzVIEZKvP77bzCXHiSzW8x2gKV8T1jnLHKBpwxJ0ph3GtDnehABA"},"schema":"pubphys.envelope/1"},"record_hash":"83b195ca4da1af80803a849c9333512657331a8fd5d31578a1524993b5054192","leaf_index":3158}