Evidence for Intermediate Polars as the origin of the Galactic Center hard X-ray emission
Abstract
Recently, NuSTAR has discovered an unresolved hard (20-40 keV) X-ray emission within the central 10 pc of the Galaxy, possibly indicating a large population of intermediate polars (IPs). Chandra and XMM-Newton measurements of both point sources and diffuse emission in the surrounding ~50 pc imply a population of magnetic CVs with white dwarf mass ~ 0.5 M⊙. We present NuSTAR broad-band (3-79 keV) spectroscopy of two nearby IPs (TV Columbae and IGR J17303-0601) as well as our investigation of various spectral models and previous X-ray observations. We argue that the observations of both the inner 10 pc and the surrounding 50 pc can be accounted for by IPs with mean white dwarf mass ~ 0.9 M⊙. We find that the lower mass derived by Chandra and XMM-Newton is an artifact of narrow energy band fitting, and the spectral features associated with these measurements naturally arise in a heavier IP population. We also discuss implications for the X-ray emission and source population in the Galactic ridge and bulge.
- Publication:
-
American Astronomical Society Meeting Abstracts #227
- Pub Date:
- January 2016
- Bibcode:
- 2016AAS...22741003H