{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"b61d4556e96f5229cc2a5ae56ff3db82633bccccb8f9b955f0c4adcb28018a2e","created":"2026-10-03T07:17:55Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["09accbaed3934624b5734eea03da8c930ea8ff01c1dddff48a801f9cf6768401","5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"8e5fc420e9d109c4be662b4bc2dd1e902725328d5a3b7313d5868208eed6a78e","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"astro.galaxy-quenching.cooling-flow","kind":"phenomenon","literature_status":"partially-resolved","n":"1","parents":[{"note":"","parent_revision":"09accbaed3934624b5734eea03da8c930ea8ff01c1dddff48a801f9cf6768401","relation":"special_case"}],"plain":"Gas at the centers of galaxy clusters radiates away its heat in less than a billion years, yet it forms stars at only a few percent of the expected rate. Jets from the central black hole carry enough energy, but how that energy spreads evenly through the gas is not known.","posed_since":"","precise":"In cool-core clusters the central gas has cooling time $t_{\\mathrm{cool}}<1\\ \\mathrm{Gyr}$ within $\\sim 100\\ \\mathrm{kpc}$, while star formation rates are $\\sim 1\\text{-}10\\ \\mathrm{percent}$ of classical cooling-flow rates of $10^2\\text{-}10^3\\ M_{\\mathrm{sun}}/\\mathrm{yr}$. Determine how jet mechanical power $P_{\\mathrm{jet}}\\sim 10^{44}\\text{-}10^{46}\\ \\mathrm{erg/s}$ is converted to heat nearly isotropically: weak shocks, sound waves, turbulent dissipation, cosmic-ray heating, or turbulent mixing. The answer is the heating rate per channel versus radius matched to the cooling rate.","problem_ref":null,"references":"","settled_by":"High-resolution X-ray spectroscopy of gas velocities and temperatures in cluster cores (XRISM and successors) combined with simulations reproducing the measured velocity structure and the heating balance.","status_note":"Jet cavity energetics match the cooling luminosity; Hitomi in 2016 measured a line-of-sight velocity dispersion of about $1.6x10^{7}\\,\\mathrm{cm}/\\mathrm{s}$ in the Perseus core, and XRISM has been measuring cluster core velocities since 2024.","title":"How do black hole jets keep cluster cores from cooling?","topic_ref":"a746179504180cf8b606d4dc0f5a5cf5a2da027fbd03f697a20b609958ec0579"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"99ac7eed9724824e1ab283652b4cb9dc7351c964ac390dbd8517403c1552cd15","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"62a3340f33c1ff816b8ac22e179175dc8d67eed0261d3b1b204ece76c6e1e3f5","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"Mt-9ckG7yWG-MkurMkiCsvvqQKPbfNMYWkylcMVq8Tmo4I4csjjpZwR66BHnNdwnP-3c_wlLYu5yR4fs0EpsAA"},"schema":"pubphys.envelope/1"},"record_hash":"99ac7eed9724824e1ab283652b4cb9dc7351c964ac390dbd8517403c1552cd15","leaf_index":542}