{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"f944773ac1d23b3c919aa529940a1820862771579c35e16f4de4aced39d34ec4","created":"2026-10-03T07:17:54Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"d597f293765e787ad6ce1a693ca4feb6053d74527abf466892f9feaae61ae416","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"identification","assisted_by":[],"external_id":"astro.disk-dynamics.phase-spiral-origin","kind":"well-posed","literature_status":"contested","n":"1","parents":[],"plain":"Gaia showed that nearby stars, plotted by height above the disk against vertical speed, trace a snail-shell spiral. It may be the ringing from a passing dwarf galaxy or from the Milky Way's own bar and arms.","posed_since":"2018","precise":"Identify the perturbation behind the $z-v_{z}$ phase spiral discovered in Gaia DR2 (Antoja et al. 2018): a Sagittarius dwarf pericenter passage, bar buckling, dark subhalos, or many stochastic perturbations, using its winding time, dependence on radius, age and guiding radius, and the satellite's mass.","problem_ref":null,"references":"","settled_by":"Self-consistent N-body models of the Milky Way with a realistic Sagittarius mass history that reproduce the spiral's amplitude, winding and radial dependence.","status_note":"","title":"Origin of the Gaia phase spiral in the Milky Way disk","topic_ref":"f19e1364f833efe76f28e89a114cdd946c8b004cdb07a402cf8e6ddc3975459a"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"f58e401e208522f093fa01890d9bab272da2f792bfb1c72b953199f4e320d19b","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"c08948a5db85e373164724b15b572f1b31423fdb1d374f194cc298f8355476db","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"XestIrAujS7MOW2cCARV7JLh38QKdNpNwmkYqklNXP2Oa4ffzS9Ycy-BxW4gunb5MbgvoNTomAH-qt3LDTh_BA"},"schema":"pubphys.envelope/1"},"record_hash":"f58e401e208522f093fa01890d9bab272da2f792bfb1c72b953199f4e320d19b","leaf_index":521}