The Initial Mass Function in the Extended Ultraviolet Disk of M83

Abstract

Using Hubble Space Telescope ACS/WFC data we present the photometry and spatial distribution of resolved stellar populations of four fields within the extended ultraviolet disk (XUV disk) of M83. These observations show a clumpy distribution of main-sequence stars and a mostly smooth distribution of red giant branch stars. We constrain the upper-end of the initial mass function (IMF) in the outer disk using the detected population of main-sequence stars and an assumed constant star formation rate (SFR) over the last 300 Myr. By comparing the observed main-sequence luminosity function to simulations, we determine the best-fitting IMF to have a power law slope $\alpha =-2.35\pm 0.3$ and an upper-mass limit ${\mathrm{M}}_{\mathrm{u}}=25_{-3}^{+17}{\mathrm{M}}_{\odot }$. This IMF is consistent with the observed H$\alpha$ emission, which we use to provide additional constraints on the IMF. We explore the influence of deviations from the constant SFR assumption, finding that our IMF conclusions are robust against all but strong recent variations in SFR, but these are excluded by causality arguments. These results, along with our similar studies of other nearby galaxies, indicate that some XUV disks are deficient in high-mass stars compared to a Kroupa IMF. There are over one hundred galaxies within 5 Mpc, many already observed with HST, thus allowing a more comprehensive investigation of the IMF, and how it varies, using the techniques developed here.

MNRAS accepted. 28 pages, 7 Tables, 19 Figures. See published article or contact third author for paper with figures at full resolution. (V2: small error in metadata corrected)

References in corpus (31)

• A systematic variation of the stellar initial mass function in early-type galaxies
• Cold gas accretion in galaxies
• The ACS Nearby Galaxy Survey Treasury
• The effect of massive binaries on stellar populations and supernova progenitors
• New PARSEC evolutionary tracks of massive stars at low metallicity: testing canonical stellar evolution in nearby star forming dwarf galaxies
• The Effects of Stellar Rotation. II. A Comprehensive Set of Starburst99 Models
• A Search for Extended Ultraviolet Disk (XUV-disk) Galaxies in the Local Universe
• A Minimum Column Density of 1 g cm^-2 for Massive Star Formation
• Cepheid Distances to SNe Ia Host Galaxies based on a Revised Photometric Zero-Point of the HST-WFPC2 and New P-L Relations and Metallicity Corrections
• The VLT-FLAMES survey of massive stars: atmospheric parameters and rotational velocity distributions for B-type stars in the Magellanic Clouds
• Variations in Stellar Clustering with Environment: Dispersed Star Formation and the Origin of Faint Fuzzies
• The ACS Nearby Galaxy Survey Treasury I. The Star Formation History of the M81 Outer Disk
• On The Extended Knotted Disks of Galaxies
• Star Cluster Catalogs for the LEGUS Dwarf Galaxies
• Double tidal disruptions in galactic nuclei
• Spitzer Observations of Star Formation in the Extreme Outer Disk of M83 (NGC5236)
• An Expanded HST/WFC3 Survey of M83: Project Overview and Targeted Supernova Remnant Search
• Discovery of Extended Main Sequence Turn-offs in Four Young Massive Clusters in the Magellanic Clouds
• On the Blue Loops of Intermediate-Mass Stars
• Discrepancies in the ages of young star clusters; evidence for mergers?
• Simulations of XUV Disks with a Star Formation Density Threshold
• Neutral hydrogen and magnetic fields in M83 observed with the SKA Pathfinder KAT-7
• Hidden Trigger for the Giant Starburst Arc in M 83?
• Big Fish in Small Ponds: Massive Stars in the Low Mass Clusters of M83
• Kiloparsec-Scale Simulations of Star Formation in Disk Galaxies III. Structure and Dynamics of Filaments and Clumps in Giant Molecular Clouds
• The initial mass function and star formation law in the outer disc of NGC 2915
• The recent star formation in NGC 6822 from HST imaging
• The star formation history of the Sculptor Dwarf Irregular Galaxy
• The radial distributions of the two main-sequence components in the young massive star cluster NGC 1856
• Stellar dynamics in the strong-lensing central galaxy of Abell 1201: A low stellar mass-to-light ratio, a large central compact mass, and a standard dark matter halo
• Characterizing dw1335-29, a recently discovered dwarf satellite of M83

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