{"paper":{"title":"The Extinction Law in SN Ia Hosts from Background Galaxy Measurements: Toward a 1% Determination of $H_0$","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["astro-ph.GA"],"primary_cat":"astro-ph.CO","authors_text":"Adam G. Riess, Alexei V. Filippenko, Dan M. Scolnic, Henry C. Ferguson, Thomas G. Brink, Weikang Zheng, Yukei S. Murakami","submitted_at":"2025-03-12T18:00:06Z","abstract_excerpt":"In the most precise distance ladder determination of $H_0$, the observed near-infrared (NIR) fluxes of Cepheids are corrected for dust, assuming that the extinction law in large, star-forming spiral hosts of Type Ia supernovae (SN Ia) is similar to the Milky Way's average value of $R_V \\approx 3.1$. Intriguingly, studies of SNe Ia often point to lower values for their hosts ($R_V \\sim 2$). Ambiguities related to $R_V$ may limit future efforts to measure $H_0$ beyond $\\sim 1\\%$ precision. To better resolve extragalactic extinction laws, we directly measure the wavelength-dependent absorption of"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2503.09702","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/2503.09702/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}