{"paper":{"title":"Evidence of a non universal stellar Initial Mass Function. Insights from HST optical imaging of 6 Ultra Faint Dwarf Milky Way Satellites","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["astro-ph.IM","astro-ph.SR"],"primary_cat":"astro-ph.GA","authors_text":"Alvio Renzini, Evan N. Kirby, Jason S. Kalirai, Jason Tumlinson, Joshua D. Simon, Kirill Tchernyshyov, Luis C. Vargas, Mario Gennaro, Marla Geha, Puragra Guhathakurta, Roberto J. Avila, Thomas M. Brown","submitted_at":"2018-01-18T19:01:17Z","abstract_excerpt":"Using deep HST/ACS observations, we demonstrate that the sub-solar stellar initial mass function (IMF) of 6 ultra-faint dwarf Milky Way Satellites (UFDs) is more bottom light than the IMF of the Milky Way disk. Our data have a lower mass limit of about 0.45 M$_{\\odot}$, while the upper limit is $\\sim 0.8$ M$_\\odot$, set by the turn-off mass of these old, metal poor systems. If formulated as a single power law, we obtain a shallower IMF slope than the \"Salpeter\" value of $-2.3$, ranging from $-1.01$ for Leo IV, to $-1.87$ for Bo\\\"otes I. The significance of such deviations depends on the galaxy"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1801.06195","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"}