Getting a Good, Hard X-ray Look at Starburst Galaxies with NuSTAR
Abstract
Hard X-ray emission from star-forming galaxies arises from a population of neutron stars and stellar-mass (and possibly intermediate-mass) black holes, however few starburst galaxies have been detected above 10 keV. The recent launch of NuSTAR, the first satellite with hard X-ray focusing optics, opens up the possibility to not only detect these objects above 10 keV for the first time but also characterize their hard X-ray properties. Here we present an overview of a NuSTAR program to survey five normal/starburst galaxies: M82, M83, NGC 3256, NGC 3310 and Arp 299 and data analysis strategies. These observations will be supplementing a NuSTAR-Chandra-VLBA campaign on NGC 253. The NuSTAR observation of M82 will likely be dominated by the ULX M82 X-1. The exposure times will range from 30 to 180 ks, with the exposure set to ensure a 10-20 keV 5-sigma detection under conservative assumptions and these observations will more likely result in strong detections of at least the brightest several sources in each galaxy. The main goals are: 1) characterize the typical starburst spectrum above 10 keV 2) identify the nature of individually-detected X-ray sources (neutron star HMXB vs. black hole candidate) 3) look for short-term (hours to weeks) variability and establish a baseline for long-term variability studies (weeks to years) 4) characterization of the unresolved contribution to the NuSTAR flux (unresolved X-ray binaries and "diffuse" emission such as inverse-Compton scattering off of cosmic rays)
- Publication:
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AAS/High Energy Astrophysics Division #13
- Pub Date:
- April 2013
- Bibcode:
- 2013HEAD...1312015P