Interstellar gas within  ~10 pc of Sagittarius A^∗

IRAP, Université de Toulouse, CNRS, 14 avenue Édouard Belin, 31400 Toulouse, France
e-mail: katia.ferriere@irap.omp.eu

Received: 3 May 2011
Accepted: 19 January 2012

Abstract

Aims. We seek to obtain a coherent and realistic three-dimensional picture of the interstellar gas out to about 10 pc of the dynamical center of our Galaxy, which is supposed to be at Sgr A^∗.

Methods. We review the existing observational studies on the different gaseous components that have been identified near Sgr A^∗, and retain all the information relating to their spatial configuration and/or physical state. Based on the collected information, we propose a three-dimensional representation of the interstellar gas, which describes each component in terms of both its precise location and morphology and its thermodynamic properties.

Results. The interstellar gas near Sgr A^∗ can be represented by five basic components, which are, by order of increasing size: (1) a central cavity with roughly equal amounts of warm ionized and atomic gases; (2) a ring of mainly molecular gas; (3) a supernova remnant filled with hot ionized gas; (4) a radio halo of warm ionized gas and relativistic particles; and (5) a belt of massive molecular clouds. While the halo gas fills  ≈80% of the studied volume, the molecular components enclose  ≈ 98% of the interstellar mass.