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

Abstract

We have analyzed three XMM-Newton observations of the central part of the unidentified TeV γ-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. Thus Src 1 and Src 2 are probably two field sources not responsible for the TeV emission. The observations were contaminated by strong straylight from a nearby bright source, and we see no clear extended X-ray emission that can be attributed to the supernova remnant G8.7-0.1, a popular possible association with the TeV source. The other possible association, the pulsar wind nebula candidate PSR J1803-2137, shows little long-term variability, compared with a previous Chandra observation. Many point sources were serendipitously detected, but most of them are probably normal stars. Three new candidate compact object systems (other than Src 1, Src 2 and PSR J1803-2137) are also found. They are far away from the TeV source and are probably also magnetic cataclysmic variables, thus unlikely to be responsible for the TeV emission.

Accepted for Publication in ApJ. 20 pages (single column), 6 figures

References in corpus (10)

• The XMM-Newton Serendipitous Survey. V. The Second XMM-Newton Serendipitous Source Catalogue
• Teraelectronvolt Astronomy
• A connection between star formation activity and cosmic rays in the starburst galaxy M 82
• Detection of Gamma Rays From a Starburst Galaxy
• Discovery of 35 New Supernova Remnants in the Inner Galaxy
• Discovery of New Interacting Supernova Remnants in the Inner Galaxy
• Hunting high and low: XMM monitoring of the eclipsing polar HU Aquarii
• Swift/XRT follow-up observations of TeV sources of the HESS Inner Galaxy survey
• TeV source HESS J1804-216 in X-rays and other wavelengths
• Chandra View of the Unidentified TeV Gamma-ray Source HESS J1804-216

Cited by in corpus (5)

• The soft gamma-ray pulsar population: an high-energy overview
• Discovery of a Highly Variable Dipping Ultraluminous X-ray source in M94
• Classification of X-ray Sources in the XMM-Newton Serendipitous Source Catalog: Objects of Special Interest
• Two new magnetic cataclysmic variables discovered in the 3XMM catalogue
• Arc-minute-scale studies of the interstellar gas towards HESSJ1804$-$216: Still an unidentified TeV $\gamma$-ray source