{"paper":{"title":"Hydrogen Radio Recombination Line Emission from M51 and NGC628","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.GA","authors_text":"Amanda A. Kepley, Dana S. Balser, L. D. Anderson, Matteo Luisi, T. M. Bania, Trey V. Wenger","submitted_at":"2018-05-29T13:41:05Z","abstract_excerpt":"We report the discovery of hydrogen radio recombination line (RRL) emission from two galaxies with star formation rates (SFRs) similar to that of the Milky Way: M51 and NGC628. We use the Green Bank Telescope (GBT) to measure $\\sim$15 Hn$\\alpha$ recombination transitions simultaneously and average these data to improve our spectral signal-to-noise ratio. We show that our data can be used to estimate the total ionizing photon flux of these two sources, and we derive their SFRs within the GBT beam: $\\Psi_{\\rm OB} = 3.46$ M$_{\\odot}$ yr$^{-1}$ for M51 and $\\Psi_{\\rm OB} = 0.56$ M$_{\\odot}$ yr$^{-"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1805.11460","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":""},"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"}