NuSTAR observations of the starburst galaxy NGC 253: constraints on diffuse inverse Compton emission
Abstract
The nearby starburst galaxy NGC 253 has been detected at GeV and TeV energies, however, the dominant emission mechanism responsible for the gamma-ray luminosity is challenging to determine from the Fermi-LAT and H.E.S.S. data alone. Understanding what fraction of the gamma-ray signal comes from hadronic processes has implications for the non-thermal energy density in actively star-forming regions in both cosmic rays and magnetic fields. The focusing hard X-ray optics of NuSTAR have enabled the most sensitive search to date for diffuse inverse Compton emission in the 10-30 keV energy range in a starburst galaxy. We discuss NuSTAR upper limits on the diffuse inverse Compton component in the context of broadband spectral models.
- Publication:
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AAS/High Energy Astrophysics Division #14
- Pub Date:
- August 2014
- Bibcode:
- 2014HEAD...1411010B