Evidence for intermediate polars as the origin of the Galactic Center hard X-ray emission

Understand

Recently, unresolved hard (20-40 keV) X-ray emission has been discovered within the central 10 pc of the Galaxy, possibly indicating a large population of intermediate polars (IPs).

• Chandra and XMM-Newton measurements in the surrounding ~50 pc imply a much lighter population of IPs with $\langle M_{\rm WD} \rangle \approx 0.5 M_\odot$.
• Here we use broad-band NuSTAR observations of two IPs: TV Columbae, which has a fairly typical but widely varying reported mass of $M_{\rm WD} \approx 0.5-1.0 M_\odot$, and IGR J17303-0601, with a heavy reported mass of $M_{\rm WD} \approx 1.0-1.2 M_\odot$.
• We investigate how varying spectral models and observed energy ranges influence estimated white dwarf mass.