Discovery of Variable Iron Fluorescence from Reflection Nebulae in the Galactic Center

Abstract

Based on three years of deep observations of the Galactic center with the Chandra X-ray Observatory, we report the discovery of changes in the intensities and morphologies of two hard X-ray nebulosities. The nebulosities are dominated by fluorescent iron emission, and are coincident with molecular clouds. The morphological changes are manifest on parsec scales, which requires that these iron features are scattered X-rays from a 2 or 3-year-long outburst of a point source (either Sgr A* or an X-ray binary) with a luminosity of at least 1e37 erg/s. The variability precludes the hypotheses that these nebulae either are produced by keV electrons bombarding molecular clouds, or are iron-rich ejecta from supernovae. Moreover, the morphologies of the reflection nebulae implies that the dense regions of the clouds are filamentary, with widths of ~0.3 pc and lengths of ~2 pc.

5 pages, 3 figures (2 color). submitted to ApJL

Cited by in corpus (4)

• Variable accretion and emission from the stellar winds in the Galactic centre
• A Catalog of Diffuse X-ray-Emitting Features within 20 pc of Sgr A*: Twenty Pulsar Wind Nebulae?
• Isolated X-ray -- infrared sources in the region of interaction of the supernova remnant IC 443 with a molecular cloud
• POLARIX: a pathfinder mission of X-ray polarimetry