Suzaku Observations of the Great Annihilator and the Surrounding Diffuse Emissions

TL;DR

This study uses Suzaku X-ray observations to analyze the Great Annihilator and surrounding diffuse emissions, revealing clumpy structures, potential X-ray fluorescence sources, and a supernova remnant candidate near the Galactic center.

Contribution

First detailed Suzaku spectral analysis of the Great Annihilator and surrounding diffuse emissions, identifying X-ray fluorescence sources and a supernova remnant candidate.

Findings

Detected two clumpy structures around the GA in FeI and SXV lines.

Identified a 6.4-keV line source likely due to external X-ray irradiation.

Proposed G359.12-0.05 as an X-ray counterpart of a supernova remnant.

Abstract

We report the Suzaku observation of 1E 1740.7-2942, a black hole candidate called the "Great Annihilator" (GA). The high-quality spectrum of Suzaku provides the severest constraints on the parameters of the GA. Two clumpy structures are found around the GA in the line images of FeI Kalpha at 6.4 keV and SXV Kalpha at 2.45 keV. One clump named M359.23-0.04 exhibits the 6.4-keV line with an equivalent width of ~ 1.2 keV, and is associated with a molecular cloud in the radio CS(J=1-0) map. Thus the 6.4-keV line from M359.23-0.04 is likely due to X-ray fluorescence irradiated by an external X-ray source. The irradiating X-rays would be either the past flare of Sagittarius A* or the bright nearby source, the GA. The other clump named G359.12-0.05 is associated with the radio supernova remnant candidate G359.07-0.02. We therefore propose that G359.12-0.05 is an X-ray counterpart of G359.07-0.02. G359.12-0.05 has a thin thermal plasma spectrum with a temperature of kT ~ 0.9 keV. The plasma parameters of G359.12-0.05 are consistent with those of a single supernova remnant in the Galactic center region.