XMM-Newton Observations of the TeV \gamma-ray Source HESS J1804-216

Understand

We have analyzed three XMM-Newton observations of the central part of the unidentified TeV \gamma-ray source HESS J1804-216.

• We focus on two X-ray sources 2XMMi J180442.0-214221 (Src 1) and 2XMMi J180432.5-214009 (Src 2), which were suggested to be the possible X-ray counterparts to the TeV source.
• We discover a 2.93 hr X-ray periodicity from Src 1, with the pulse profile explained with a self-eclipsing pole in an eclipsing polar.
• Src 2 exhibits a strong Fe emission line (FWHM ~0.3 keV and equivalent width ~0.8 keV) and large X-ray variability on timescales of hours and is probably an intermediate polar.