No X-Ray Excess from the HESS J1741-302 Region except a New Intermediate Polar Candidate

TL;DR

This study used Suzaku observations to identify a new intermediate polar candidate near HESS J1741-302, finding no X-ray excess from the gamma-ray source but revealing a magnetized white dwarf binary with characteristic pulsations and iron lines.

Contribution

The paper reports the discovery of a new intermediate polar candidate with specific X-ray spectral features and pulsations, providing insights into the nature of the gamma-ray source region.

Findings

No diffuse or point-like X-ray sources detected from HESS J1741-302's bright emission peak.

Identification of Suzaku J174035.6-301416 as a likely intermediate polar with 432.1 s pulsation.

Detection of iron Kα emission lines indicating a magnetized white dwarf binary.

Abstract

With the Suzaku satellite, we observed an unidentified TeV gamma-ray source HESS J1741$-$302 and its surroundings. No diffuse or point-like X-ray sources are detected from the bright southern emission peak of HESS J1741$-$302. From its neighborhood, we found a new intermediate polar candidate at the position of $(\alpha, \delta)_{\rm J2000.0} = (\timeform{17h40m35.6s}, \timeform{-30D14m16s})$, which is designated as Suzaku J174035.6$-$301416. The spectrum of Suzaku J174035.6$-$301416 exhibits emission lines at the energy of 6.4, 6.7 and 7.0 keV, which can be assigned as the K$\alpha$ lines from neutral, He-like and H-like iron, respectively. A coherent pulsation is found at a period of 432.1 $\pm$ 0.1 s. The pulse profile is quasi-sinusoidal in the hard X-ray band (4$-$8 keV), but is more complicated in the soft X-ray band (1$-$3 keV). The moderate period of pulsation, the energy flux, and the presence of the iron K$\alpha$ lines indicate that Suzaku J174035.6$-$301416 is likely an intermediate polar, a subclass of magnetized white dwarf binaries (cataclysmic variables). Based on these discoveries, we give some implications on the origin of GCDX and brief comments on HESS J1741$-$302 and PSR B1737$-$30.