RT Journal Article T1 The universal initial mass function in the extended ultraviolet disk of M83 A1 Koda, Jin A1 Yagi, Masafumi A1 Boissier, Samuel A1 Gil de Paz, Armando A1 Imanishi, Masatoshi A1 Meyer, Jennifer Donovan A1 Madore, Barry F. A1 Thilker, David A. AB We report deep Subaru Hα observations of the extended ultraviolet (XUV) disk of M83. These new observations enable the first complete census of very young stellar clusters over the entire XUV disk. Combining Subaru and Galaxy Evolution Explorer data with a stellar population synthesis model, we find that (1) the standard, but stochastically sampled, initial mass function (IMF) is preferred over the truncated IMF because there are low-mass stellar clusters (10^2-3 M_☉) that host massive O-type stars; (2) the standard Salpeter IMF and a simple aging effect explain the counts of far-UV (FUV)-bright and Hα-bright clusters with masses >10^3 M_☉; and (3) the Hα-to-FUV flux ratio over the XUV disk supports the standard IMF. 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Data analyses were in part carried out on the common use data analysis computer system at the Astronomical Data Center (ADC) of the National Astronomical Observatory of Japan. This work is based in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. Some of the data presented in this paper were obtained from the Multimission Archive at the Space Telescope Science Institute (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Support for MAST for non-HST data is provided by the NASA Office of Space Science via grant NNX09AF08G and by other grants and contracts. NO Ministerio de Ciencia e Innovación (MICINN), España NO National Aeronautics and Space Administration (NASA) NO Consolider-Ingenio Program NO Programa Ramón y Cajal, MICINN DS Docta Complutense RD 4 may 2024