Suzaku Spectroscopy of an X-Ray Reflection Nebula and a New Supernova Remnant Candidate in the Sgr B1 Region

TL;DR

This study used Suzaku/XIS to analyze the Sgr B1 region near the Galactic center, discovering a new supernova remnant candidate and an X-ray reflection nebula, revealing extended hot plasma and historical activity of Sgr A*.

Contribution

The paper reports the first detection of a new supernova remnant candidate and an X-ray reflection nebula in the Sgr B1 region, and demonstrates the extension of hot plasma from the Galactic center.

Findings

Detection of Fe XXV and Fe XXVI emission lines across Sgr B1 and B2.

Discovery of a new supernova remnant candidate G0.42-0.04.

Identification of an X-ray reflection nebula M0.51-0.10 with historical Sgr A* activity evidence.

Abstract

We made a 100 ks observation of the Sagittarius (Sgr) B1 region at (l, b) = (0.5, -0.1) near to the Galactic center (GC) with the Suzaku/XIS. Emission lines of S XV, Fe I, Fe XXV, and Fe XXVI were clearly detected in the spectrum. We found that the Fe XXV and Fe XXVI line emissions smoothly distribute over the Sgr B1 and B2 regions connecting from the GC. This result suggests that the GC hot plasma extends at least up to the Sgr B region with a constant temperature. There are two diffuse X-ray sources in the observed region. One of the two (G0.42-0.04) is newly discovered, and exhibits a strong S XV Ka emission line, suggesting a candidate for a supernova remnant located in the GC region. The other one (M0.51-0.10), having a prominent Fe I Ka emission line and a strongly absorbed continuum, is likely to be an X-ray reflection nebula. There is no near source bright enough to irradiate M0.51-0.10. However, the Fe I Ka emission can be explained if Sgr A* was ~ 10^6 times brighter 300 years ago, the light travel time for 100 pc to M0.51-0.10, than it is at present.