Dissecting X-ray-emitting Gas around the Center of our Galaxy

TL;DR

This study analyzes 3 million seconds of Chandra X-ray data to understand the gas around our Galaxy's supermassive black hole, revealing an outflow and ruling out certain star-based origins, thus informing accretion models.

Contribution

It provides detailed X-ray observations of the Galactic Center's SMBH, constraining accretion models and ruling out star-based emission origins.

Findings

X-ray emission aligns with a star disk but isn't from low-mass stars.

Weak Fe Kalpha line indicates an outflow from the SMBH.

Results constrain radiatively inefficient accretion models.

Abstract

Most supermassive black holes (SMBHs) are accreting at very low levels and are difficult to distinguish from the galaxy centers where they reside. Our own Galaxy's SMBH provides a uniquely instructive exception, and we present a close-up view of its quiescent X-ray emission based on 3 mega-second of Chandra observations. Although the X-ray emission is elongated and aligns well with a surrounding disk of massive stars, we can rule out a concentration of low-mass coronally active stars as the origin of the emission based on the lack of predicted Fe Kalpha emission. The extremely weak H-like Fe Kalpha line further suggests the presence of an outflow from the accretion flow onto the SMBH. These results provide important constraints for models of the prevalent radiatively inefficient accretion state.