Discovery of new X-ray sources near the unidentified gamma-ray source HESS J1841-055

HESS J1841$-$055 is a diffuse unidentified gamma-ray source with the size of $\sim\,1.3^{\circ}\times\,1^{\circ}$. No conclusive counterpart in other wavelengths has so far detected. To search for X-rays responsible for the TeV emission, the Suzaku observations were conducted, which covered a half region of the HESS source. In the soft band (0.5-2.0 keV), we discovered a diffuse emission, Suzaku J1840.2$-$0552, with the size of $\sim10'$. Since its spectrum was fitted by an optically thin thermal plasma model, Suzaku J1840.2$-$0552 is likely to be a supernova remnant. We also discovered an extended source, Suzaku J1840.2$-$0544, in the hard band (2.0-8.0 keV) with an emission line at 6.1 keV. From the spectral feature and large interstellar absorption, this source is likely to be a cluster of galaxies behind the Galactic plane at the red-shift of $\sim$0.09. The other diffuse source spatially overlaps with the SNR candidate G26.6$-$0.2, which shows a non-thermal dominant spectrum. Since no other candidate is found in the hard X-ray band, we infer that these largely extended sources could be possible counterparts of HESS J1841$-$055.

K. K. Nobukawa, M. Nobukawa, T. G. Tsuru, K. Koyama · 2015