{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"c0add670e49d3a0d7042b8520194166909f9da46618a76efa2a05b22e9d66fd4","created":"2026-10-03T07:17:54Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"663b211cd2a1da95ad9bb939b6d13d52cfa5a3938e44ce7854513b581ed01ad0","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":"1","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 $T \\sim 1e4\\ \\mathrm{K}$ moving through halo gas at $T \\sim 1e6\\ \\mathrm{K}$ 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":null,"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":"0def120d1b6025e505d1b17c3590b27372b9f92290b62b2df74ed8a1826b48cb"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"5151e458286025276980eabd28bfb219be7a4a4a20485edd141558d5be08f14d","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"475cc3177372b99daf2e59ddf886d68b1dcb0155f48a633d2f0dd2fbdba80fbb","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"7Uc5UowOTe_3KdNP271wMaM26nGgs5CXCS0YeYnzueeMntXU-6xCI3u7-TnFvcgD1w7AUh3RTXfXqoPnNUfIDg"},"schema":"pubphys.envelope/1"},"record_hash":"5151e458286025276980eabd28bfb219be7a4a4a20485edd141558d5be08f14d","leaf_index":490}