THE UNIVERSAL INITIAL MASS FUNCTION IN THE EXTENDED ULTRAVIOLET DISK OF M83

Journal Article · Tue Apr 10 04:00:00 EDT 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/749/1/20· OSTI ID:22020510

Koda, Jin; Meyer, Jennifer Donovan ^[1]; Yagi, Masafumi ^[2]; Boissier, Samuel ^[3]; Gil de Paz, Armando ^[4]; Imanishi, Masatoshi ^[5]; Madore, Barry F ^[6]

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1. Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800 (United States)
2. Optical and Infrared Astronomy Division, National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)
3. Laboratoire d'Astrophysique de Marseille (LAM), Universite Aix-Marseille and CNRS, UMR7326, 38 rue F. Joliot-Curie, 13388 Marseille Cedex 13 (France)
4. Departamento de Astrofisica y CC. de la Atmosfera, Universidad Complutense de Madrid, Avda. de la Complutense s/n, Madrid E-28040 (Spain)
5. Subaru Telescope, 650 North A'ohoku Place, Hilo, HI 96720 (United States)
6. Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)

We report deep Subaru H{alpha} 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{sup 2-3} M{sub Sun }) 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 H{alpha}-bright clusters with masses >10{sup 3} M{sub Sun }; and (3) the H{alpha}-to-FUV flux ratio over the XUV disk supports the standard IMF. To reach conclusion (2), we assumed instantaneous cluster formation and a constant cluster formation rate over the XUV disk. The Subaru Prime Focus Camera covers a large area even outside the XUV disk-far beyond the detection limit of the H I gas. This enables us to statistically separate the stellar clusters in the disk from background contamination. The new data, model, and previous spectroscopic studies provide overall consistent results with respect to the internal dust extinction (A{sub V} {approx} 0.1 mag) and low metallicity ({approx}0.2 Z{sub Sun }) using the dust extinction curve of the Small Magellanic Cloud. The minimum cluster mass for avoiding the upper IMF incompleteness due to stochastic sampling and the spectral energy distributions of O, B, and A stars are discussed in the Appendices.

• OSTI ID: 22020510
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 749; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ENERGY SPECTRA
EXTREME ULTRAVIOLET RADIATION
GALACTIC EVOLUTION
LUMINOSITY
MAGELLANIC CLOUDS
MASS
STAR CLUSTERS
STARS
STOCHASTIC PROCESSES