{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"4c81f821630a4fc622b59b700c9f154f1e30c8f9ac0cde98f326302af3e5a01f","created":"2026-10-03T07:17:55Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["09accbaed3934624b5734eea03da8c930ea8ff01c1dddff48a801f9cf6768401","5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"6b9bb97c76423ed5007bc0b218664b38d41ea995e00ec55b72ca25c9b2be27e0","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"astro.galaxy-quenching.early-quiescent","kind":"phenomenon","literature_status":"contested","n":"1","parents":[{"note":"","parent_revision":"09accbaed3934624b5734eea03da8c930ea8ff01c1dddff48a801f9cf6768401","relation":"special_case"}],"plain":"JWST found massive galaxies that had already finished forming stars when the universe was under a billion years old. Making that many stars and then stopping so quickly is hard to reproduce in models.","posed_since":"","precise":"JWST has confirmed massive quiescent galaxies up to $z = 7.29$ (RUBIES-UDS-QG-z7, $M_{*} >\\sim 10^{10} M_{\\mathrm{sun}}$); quiescent number densities exceed most models by up to $\\sim 1\\,\\mathrm{dex}$ at $z \\sim 3-5$, and the abundance implied at $z \\sim 7$ is more than 100 times any model prediction (Weibel et al. 2025). Determine whether standard Lambda-CDM halo abundances with physical feedback can produce such galaxies, which requires star formation rates of hundreds of $M_{\\mathrm{sun}}/\\mathrm{yr}$ followed by quenching within $\\sim 10^{8}\\,\\mathrm{yr}$, or whether stellar masses and ages are biased by the assumed initial mass function or AGN light.","problem_ref":null,"references":"","settled_by":"Spectroscopic stellar masses, ages and number densities for a complete sample at $z > 4$ compared with simulations that use the same selection, giving agreement or a quantified excess.","status_note":"As of 2026 initial mass function variation, AGN contamination of the light and small-sample statistics are proposed explanations; none is established.","title":"How did massive galaxies stop forming stars within 700 Myr?","topic_ref":"a746179504180cf8b606d4dc0f5a5cf5a2da027fbd03f697a20b609958ec0579"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"0939bd1b4e72efeb124202312bfc8150cacd240ea4effcfa0c49ea95a7342c40","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"3b0742ce63bb52bfea625ca05765dc6ad9378d2db37f861db7db2e870a478965","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"pqlYo4BqAoOgCMikoGalnJ7kpHbDzeiNos5WPpl8csqsMkdvCq6L_fp1usl-6IXdYbg9TDhqwYskXDS3MP9_BQ"},"schema":"pubphys.envelope/1"},"record_hash":"0939bd1b4e72efeb124202312bfc8150cacd240ea4effcfa0c49ea95a7342c40","leaf_index":543}