X-Ray Observation of Very High Energy Gamma-Ray Source, HESS J1745-303, with Suzaku

TL;DR

This study uses Suzaku X-ray observations to analyze the unidentified TeV gamma-ray source HESS J1745-303, discovering potential iron line emission and discussing its possible association with the Galactic Center's molecular clouds and emission mechanisms.

Contribution

The paper presents the first Suzaku X-ray observations of HESS J1745-303, identifying iron line excess and constraining diffuse X-ray emission, providing insights into the source's nature and its relation to Galactic Center activity.

Findings

Possible iron line excess associated with HESS J1745-303 region A

Stringent upper limit on diffuse X-ray emission from the region

Detection and characterization of nearby supernova remnants

Abstract

Suzaku observations of a TeV unidentified (unID) source, HESS J1745-303, are presented. A possible excess of neutral iron line emission is discovered, and is likely associated with the main part of HESS J1745-303, named "region A". It may be an X-ray reflection nebula where the X-rays from previous Galactic Center (GC) activity are reflected by a molecular cloud. This result further strengthens the assumption that the molecular cloud which is spatially coincident with region A of HESS J1745-303 is located in the GC region. The TeV emission from molecular clouds is reminiscent of the diffuse TeV gamma-rays from the GC giant molecular clouds, and it could have the same emission mechanism. With deep exposure mapping observations by Suzaku, a tight upper-limit on the 2-10 keV continuum diffuse emission from region A is obtained, as 2.1x10^-13ergs s^-1cm^-2. The flux ratio between 1-10 TeV and 2-10 keV is larger than 4. Possible scenarios to reproduce wide-band spectra from keV to TeV are examined. Thermal X-rays from nearby two old supernova remnants, G359.0-0.9 and G359.1-0.5, are detected, and their emission properties are well determined in the present study with deep exposure.