{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"0e722867f145243ab9a7594b1e33f93abfc84862ce76b6bbba36cd2d43255cc9","created":"2026-10-03T07:18:02Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011","ed264645728bed1ec687ad4bd3875390250b8f5cab07bf83f47c6553d9b6de0f"],"salt":"2648fb7779ad9413644cfd3babe1322d047cff33df139be5e2d15676516848e7","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"value","assisted_by":[],"external_id":"cosmo.hubble-tension.local-void","kind":"well-posed","literature_status":"contested","n":"1","parents":[{"note":"","parent_revision":"ed264645728bed1ec687ad4bd3875390250b8f5cab07bf83f47c6553d9b6de0f","relation":"special_case"}],"plain":"If the Milky Way lies inside a huge region with less matter than average, nearby galaxies recede faster and the measured local expansion rate comes out high. Galaxy counts suggest such a void, while supernova data mostly argue against it.","posed_since":"2013","precise":"Keenan, Barger and Cowie (2013, ApJ 775, 62) found the local K-band luminosity density about 1.5 times lower than at $z > 0.1$, suggesting an underdensity to about 300 Mpc. In linear theory $\\Delta H/H \\sim -f\\delta/3$ with growth rate $f \\sim 0.5$, so $\\delta \\sim -0.3$ would raise local h by about 5 percent. Determine the mean matter density contrast $\\delta$ within radii 100 to 600 Mpc around the Milky Way with uncertainty below 0.05, and the induced shift in local $h$, from galaxy counts with consistent selection, peculiar velocities and supernova Hubble residuals.","problem_ref":null,"references":"","settled_by":"Full-sky galaxy redshift and peculiar-velocity surveys (for example 4MOST, DESI peculiar velocities, WALLABY) combined with supernova Hubble residuals as a function of distance and direction.","status_note":"Kenworthy, Scolnic and Riess (2019) found supernova distances inconsistent with such a void at 4 to 5 $\\sigma$, while Haslbauer, Banik and Kroupa (2020, MNRAS 499, 2845) argue that the void and the $H0$ tension together conflict with LCDM.","title":"Does a local underdensity bias the locally measured Hubble constant?","topic_ref":"7274d4f6495a643569c4fecb6957a3a928df8172b93a2b26d1dc5043075bd891"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"25cd9fe74d8602e0b35322f17c07c705c2af730a6ad2ea62fbb90388298411bd","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"2a50a81f0527dd83af5c8fc3f7c1ac299c09a2d75d44a915134b6ebb4b484fd1","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"kBfRYbinXDSYWrgGMoAJAJUckK46yqNqEg2Ld93yDkeVQYn6otOX2Ct_ZxHIar1UEMoD6Ff_bSPb47LYIjj2Bw"},"schema":"pubphys.envelope/1"},"record_hash":"25cd9fe74d8602e0b35322f17c07c705c2af730a6ad2ea62fbb90388298411bd","leaf_index":1259}