{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"51f7f5719ad07332970f13547f0d4f728840a9f33c8b7e79461deffbcc9cf90a","created":"2026-10-03T07:18:02Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"1a15aa8f42bf619336718b90d5983aabd813aa21718d6601432f3623101dd132","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"cosmo.primordial-black-holes.earth-mass-events","kind":"well-posed","literature_status":"open","n":"1","parents":[],"plain":"Surveys watching millions of stars see a few brightenings lasting less than a day, caused by passing objects about as heavy as the Earth. They are usually attributed to planets drifting free of any star, but primordial black holes would produce identical events.","posed_since":"2019","precise":"OGLE bulge data contain 6 ultrashort events that Niikura et al. (2019, arXiv:1901.07120) reproduce with Earth-mass PBHs forming about a percent of dark matter, while MOA (Sumi et al. 2023, arXiv:2303.08280) attributes such events to about 21 free-floating planets per star. Determine $f_{\\mathrm{PBH}} = \\Omega_{\\mathrm{PBH}} / \\Omega_{c}$ for $M = 1e-7\\ \\text{to}\\ 1e-5\\ M_{\\mathrm{sun}}$ ($2e26\\ \\text{to}\\ 2e28\\ \\mathrm{g}$) by separating lens populations through event-rate dependence on direction (bulge, disk, halo, lines of sight to the LMC and M31) and through lens-distance information.","problem_ref":null,"references":"","settled_by":"Nancy Grace Roman Space Telescope microlensing statistics with parallax for short events, compared between the bulge and halo-dominated lines of sight.","status_note":"Mroz et al. (2024, Nature 632, 749) bound $f_{\\mathrm{PBH}} < 0.1$ for $1.3e-5 \\text{ to } 860\\,M_{\\mathrm{sun}}$ toward the LMC, leaving the Earth-mass range less constrained.","title":"Are ultrashort microlensing events caused by planets or primordial black holes?","topic_ref":"9ab792b7e278762046677161a5c3d97a4c12042fe341bebc00b0f937c2c50d7a"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"df1d5ed9018a2058fa8ad71cab68f9b9f30b31d512782cb46fb0f81c38030fc9","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"b62d4307d23ea80d8ca48fc7b867b9405779ea3fde80ffc10dcfb089f95dca57","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"IKy0CYHyNqJaXqrbsGRziczYDuL4JSfPgn1EFQkvbVG6dwN3SlEf8hJvMWCOMCykAafqy57JXcX3z3mM16IkDw"},"schema":"pubphys.envelope/1"},"record_hash":"df1d5ed9018a2058fa8ad71cab68f9b9f30b31d512782cb46fb0f81c38030fc9","leaf_index":1271}