BIG FISH IN SMALL PONDS: MASSIVE STARS IN THE LOW-MASS CLUSTERS OF M83

We have used multi-wavelength Hubble Space Telescope WFC3 data of the starbursting spiral galaxy M83 in order to measure variations in the upper end of the stellar initial mass function (uIMF) using the production rate of ionizing photons in unresolved clusters with ages $\leq$ 8 Myr. As in earlier papers on M51 and NGC 4214, the upper end of the stellar IMF in M83 is consistent with an universal IMF, and stochastic sampling of the stellar populations in the $\lessapprox$ 10$^{3}$ Msun clusters are responsible for any deviations in this universality. The ensemble cluster population, as well as individual clusters, also imply that the most massive star in a cluster does not depend on the cluster mass. In fact, we have found that these small clusters seem to have an over-abundance of ionizing photons when compared to an expected universal or truncated IMF. This also suggests that the presence of massive stars in these clusters does not affect the star formation in a destructive way.

[1]  C. Conroy,et al.  CONFIRMATION OF ENHANCED DWARF-SENSITIVE ABSORPTION FEATURES IN THE SPECTRA OF MASSIVE ELLIPTICAL GALAXIES: FURTHER EVIDENCE FOR A NON-UNIVERSAL INITIAL MASS FUNCTION , 2011, 1102.3431.

[2]  Edward L. Fitzpatrick,et al.  Correcting for the Effects of Interstellar Extinction , 1998, astro-ph/9809387.

[3]  C. Leitherer,et al.  THE EFFECTS OF STELLAR ROTATION. II. A COMPREHENSIVE SET OF STARBURST99 MODELS , 2014, 1403.5444.

[4]  R. Kotulla,et al.  STOCHASTIC STELLAR CLUSTER INITIAL MASS FUNCTIONS: MODELS AND IMPACT ON INTEGRATED CLUSTER PARAMETER DETERMINATION , 2013, 1310.4936.

[5]  J. Lee,et al.  On how leakage can affect the star formation rate estimation using Hα luminosity , 2012, 1204.4502.

[6]  Terry D. Oswalt,et al.  Planets, Stars and Stellar Systems , 2013 .

[7]  M. Gieles,et al.  Stellar clusters in M83: formation, evolution, disruption and the influence of the environment , 2011, 1109.6015.

[8]  G. Gavazzi,et al.  HIGH-MASS STAR FORMATION IN NORMAL LATE-TYPE GALAXIES: OBSERVATIONAL CONSTRAINTS TO THE INITIAL MASS FUNCTION , 2009, 0910.3521.

[9]  P. Kroupa,et al.  The relation between the most-massive star and its parental star cluster mass , 2009, 0909.1555.

[10]  P. Kroupa,et al.  Galactic-Field Initial Mass Functions of Massive Stars , 2003 .

[11]  J. Eldridge.  Stochasticity, a variable stellar upper mass limit, binaries and star formation rate indicators , 2011, 1106.4311.

[12]  K. Glazebrook,et al.  Evidence for a Nonuniversal Stellar Initial Mass Function from the Integrated Properties of SDSS Galaxies , 2007, 0711.1309.

[13]  Douglas P. Finkbeiner,et al.  MEASURING REDDENING WITH SLOAN DIGITAL SKY SURVEY STELLAR SPECTRA AND RECALIBRATING SFD , 2010, 1012.4804.

[14]  O. I. Wong,et al.  EVIDENCE FOR A NONUNIFORM INITIAL MASS FUNCTION IN THE LOCAL UNIVERSE , 2009, 0902.0384.

[15]  A. Kinney,et al.  The Dust Content and Opacity of Actively Star-forming Galaxies , 1999, astro-ph/9911459.

[16]  R. Davies,et al.  Systematic variation of the stellar initial mass function in early-type galaxies , 2012, Nature.

[17]  Abhijit Saha,et al.  The Cepheid Distance to NGC 5236 (M83) with the ESO Very Large Telescope , 2003 .

[18]  B. Whitmore,et al.  ANALYZING STAR CLUSTER POPULATIONS WITH STOCHASTIC MODELS: THE HUBBLE SPACE TELESCOPE/WIDE FIELD CAMERA 3 SAMPLE OF CLUSTERS IN M83 , 2012, 1202.3135.

[19]  J. M. Apell'aniz.  Accepted for publication in the Astrophysical Journal Biases on initial mass function determinations. II. Real multiple systems and chance superpositions 1 , 2022 .

[20]  M. Dopita,et al.  THE LUMINOSITY, MASS, AND AGE DISTRIBUTIONS OF COMPACT STAR CLUSTERS IN M83 BASED ON HUBBLE SPACE TELESCOPE/WIDE FIELD CAMERA 3 OBSERVATIONS , 2010, 1007.5237.

[21]  Cambridge,et al.  A Universal Stellar Initial Mass Function? A critical look at variations in extreme environments , 2010, 1001.2965.

[22]  David W. Hogg,et al.  THE PANCHROMATIC HUBBLE ANDROMEDA TREASURY. IV. A PROBABILISTIC APPROACH TO INFERRING THE HIGH-MASS STELLAR INITIAL MASS FUNCTION AND OTHER POWER-LAW FUNCTIONS , 2012, 1211.6105.

[23]  M. Dopita,et al.  THE RESOLVED STELLAR POPULATION IN 50 REGIONS OF M83 FROM HST/WFC3 EARLY RELEASE SCIENCE OBSERVATIONS , 2012, 1204.6045.

[24]  J. C. Lee,et al.  A METHOD FOR MEASURING VARIATIONS IN THE STELLAR INITIAL MASS FUNCTION , 2010, 1007.3188.

[25]  C. Lada,et al.  Embedded Clusters in Molecular Clouds , 2003, astro-ph/0301540.

[26]  J. Gallagher,et al.  On the formation of star clusters in the merger NGC 6240 , 2003, astro-ph/0306446.

[27]  Mark Clampin,et al.  The Low End of the Initial Mass Function in Young Large Magellanic Cloud Clusters. I. The Case of R136 , 2000 .

[28]  C. Leitherer,et al.  A LIBRARY OF THEORETICAL ULTRAVIOLET SPECTRA OF MASSIVE, HOT STARS FOR EVOLUTIONARY SYNTHESIS , 2010, 1006.5624.

[29]  M. Oey.  ON THE ORIGIN OF THE SALPETER SLOPE FOR THE INITIAL MASS FUNCTION , 2011, 1108.2287.

[30]  H. Ferguson,et al.  THE STELLAR INITIAL MASS FUNCTION OF ULTRA-FAINT DWARF GALAXIES: EVIDENCE FOR IMF VARIATIONS WITH GALACTIC ENVIRONMENT , 2013, 1304.7769.

[31]  Benjamin D. Johnson,et al.  MODELING THE EFFECTS OF STAR FORMATION HISTORIES ON Hα AND ULTRAVIOLET FLUXES IN NEARBY DWARF GALAXIES , 2011, 1109.2905.

[32]  F. Bresolin,et al.  Optical Spectroscopy of Metal-rich H II Regions and Circumnuclear Hot Spots in M83 and NGC 3351 , 2002, astro-ph/0202383.

[33]  Mark R. Krumholz,et al.  AN INITIAL MASS FUNCTION STUDY OF THE DWARF STARBURST GALAXY NGC 4214 , 2013, 1302.5006.

[34]  N. Bastian,et al.  Resolved photometry of extragalactic young massive star clusters , 2011, 1106.4560.

[35]  P. Kroupa,et al.  The galaxy-wide initial mass function of dwarf late-type to massive early-type galaxies , 2013, 1309.6634.

[36]  J. Alves,et al.  No evidence of mass segregation in massive young clusters , 2008, 0811.3213.

[37]  S. Sakai,et al.  An Hα Imaging Survey of Galaxies in the Local 11 Mpc Volume , 2004, 0807.2035.

[38]  Linda J. Smith,et al.  M82-F: a doomed super star cluster? , 2001, astro-ph/0104429.

[39]  P. Kroupa.  On the variation of the initial mass function , 2000, astro-ph/0009005.

[40]  B. Popescu,et al.  THE RANGE OF VARIATION OF THE MASS OF THE MOST MASSIVE STAR IN STELLAR CLUSTERS DERIVED FROM 35 MILLION MONTE CARLO SIMULATIONS , 2013, 1311.5264.

[41]  B. Elmegreen,et al.  The cluster birthline in M33 , 2009, 0901.1530.

[42]  S. Bamford,et al.  Galaxy and Mass Assembly (GAMA): the star formation rate dependence of the stellar initial mass function , 2011, 1104.2379.

[43]  M. Cerviño,et al.  Modeling the ionizing spectra of H II regions: individual stars versus stellar ensembles , 2010, 1010.3031.

[44]  R. Walterbos,et al.  THE STELLAR MASS DISTRIBUTION IN THE GIANT STAR FORMING REGION NGC 346 , 2007, 0710.0558.

[45]  P. Hopkins,et al.  The Origin and Universality of the Stellar Initial Mass Function , 2013, 1312.5326.

[46]  Benjamin D. Johnson,et al.  COMPARISON OF Hα AND UV STAR FORMATION RATES IN THE LOCAL VOLUME: SYSTEMATIC DISCREPANCIES FOR DWARF GALAXIES , 2009, 0909.5205.

[47]  Extinction radial profiles of M83 from GALEX ultraviolet imaging , 2004, astro-ph/0411375.

[48]  M. Fumagalli,et al.  SLUG—STOCHASTICALLY LIGHTING UP GALAXIES. I. METHODS AND VALIDATING TESTS , 2011, 1106.3072.

[49]  J. Anderson,et al.  MIXED POPULATIONS IN GLOBULAR CLUSTERS: ET TU, 47 TUC? , 2009, 0904.1626.

[50]  Thierry Montmerle,et al.  From darkness to light : origin and evolution of young stellar clusters : proceedings of a meeting held in Cargèse, Corsica, France, 3-8 April 2000 , 2001 .

[51]  B. Elmegreen.  On the Similarity between Cluster and Galactic Stellar Initial Mass Functions , 2006, astro-ph/0605520.

[52]  P. Kroupa,et al.  The stellar and sub-stellar IMF of simple and composite populations , 2011, 1112.3340.

[53]  The University of Toledo,et al.  USING Hα MORPHOLOGY AND SURFACE BRIGHTNESS FLUCTUATIONS TO AGE-DATE STAR CLUSTERS IN M83 , 2011, 1103.4026.

[54]  Denis Foo Kune,et al.  Starburst99: Synthesis Models for Galaxies with Active Star Formation , 1999, astro-ph/9902334.

[55]  M. Fumagalli,et al.  STOCHASTIC STAR FORMATION AND A (NEARLY) UNIFORM STELLAR INITIAL MASS FUNCTION , 2011, 1105.6101.