{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"13d723dbd23f0dd2886a287746753145b26d794ccc127337febf95e36f42b17d","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5151e458286025276980eabd28bfb219be7a4a4a20485edd141558d5be08f14d","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"d77ba8445e97a413a0fd15e3c3a6d3fc121f1f0ce2a85eac66f896d82ce84f7b","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"astro.circumgalactic-medium.cold-cloud-survival","kind":"well-posed","literature_status":"partially-resolved","n":"2","parents":[],"plain":"Halos contain cool clouds at about ten thousand degrees moving through gas a hundred times hotter. Such clouds should be shredded and evaporated quickly, yet they are common.","posed_since":"","precise":"Clouds at $T \\sim 10^{4}\\ \\mathrm{K}$ moving through halo gas at $T \\sim 10^{6}\\ \\mathrm{K}$ should be destroyed by Kelvin-Helmholtz instabilities in a few cloud-crushing times $t_{\\mathrm{cc}}$. Simulations find clouds grow when the mixing-layer cooling time is short compared with $t_{\\mathrm{cc}}$ (Gronke and Oh 2018). Determine whether this criterion, modified by magnetic fields, thermal conduction and cosmic rays, predicts the observed cloud sizes, velocities and covering fractions.","problem_ref":"5151e458286025276980eabd28bfb219be7a4a4a20485edd141558d5be08f14d","references":"","settled_by":"Converged radiative MHD simulations with conduction and cosmic rays that match absorption-line cloud sizes and kinematics, tested against small-scale structure seen in lensed quasar sightlines.","status_note":"A survival criterion for idealized clouds is established in simulations; its validity with full halo physics and its observational test remain open.","title":"How do cold gas clouds survive inside hot galactic halos?","topic_ref":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"8f1f83e8c38c01c0c7f1e541f7b3124d38f881956c1aaf795da6b3018742bf5a","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"1de72e49a99ba022792e1fafbba4de270362441d9ad12a777cc7eaba4f2bba77","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"bTROrxrior4ZAlmoc1EcVlxjI_7qgFwhjWvUKuWcWXBcs1HqPX3oW58my9xbA8N3siXgyElsXKtSRO-E3rcTDA"},"schema":"pubphys.envelope/1"},"record_hash":"8f1f83e8c38c01c0c7f1e541f7b3124d38f881956c1aaf795da6b3018742bf5a","leaf_index":2306}