A NuSTAR Perspective on the Star-forming Galaxy M83
Abstract
We present results from NuSTAR observations (cumulative 420 ks) of the late-type galaxy M83. This is the first investigation of the spatially-resolved hard X-ray emission from a galaxy with properties comparable to those of the Milky Way (MW). M83 is included in the NuSTAR starburst/normal galaxy survey sample, which is comprised of six nearby galaxies spanning the star formation rate (SFR) range of 1 to 80 Msol/yr. We have resolved several off-nuclear point sources in our M83 NuSTAR observations. To characterize the nature of these X-ray point sources, we construct color-color and luminosity-color diagrams in NuSTAR bandpasses and compare them with well studied binaries in the MW. The previously reported ULX in M83, which is known to have a low-mass counterpart, showed similar colors and luminosity to other ULXs observed by NuSTAR. The majority of the remaining NuSTAR point sources are likely to be black hole binaries in intermediate accretion states. We found that M83 has an integrated galaxy-wide X-ray spectrum that rapidly declines at hard X-ray energies (>10 keV). This is due to majority contributions from the few brightest X-ray binaries, which have steep X-ray spectra and dominate the total hard X-ray emission of the galaxy. Finally, we construct a first empirical calibration of the hard X-ray luminosity (10-30 keV)/SFR correlation including nearby galaxies in the archive in addition to other starburst samples (NGC253, Arp299, NGC3310, and M82).
- Publication:
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AAS/High Energy Astrophysics Division #14
- Pub Date:
- August 2014
- Bibcode:
- 2014HEAD...1440306Y