Interstellar gas within ∼10 pc of Sagittarius A *

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. © 2012 ESO.