What is Sgr A*?

What is Sgr A*?

The Starved Black Hole in the Center of the Milky Way.

Heino Falcke

Max-Planck Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany

in: "Unsolved Problems of the Milky Way", IAU Symp. 169, L. Blitz (ed.), Kluwer, p. 169-180


Sgr A* is the unique 1 Jy flat spectrum radio point source located at the dynamical center of the Galaxy and in the very center of the central star cluster (Eckart et al. 1993). Due to its unusual appearance it has long been speculated that this source is powered by a supermassive black hole -- an object whose presence has been suspected to reside in the nuclei of many other galaxies as well. Its mass is believed to be as large as M_bh=2 10^6 M_sun (e.g. Genzel \& Townes 1987) while a lower limit of M_bh > 200-2000 M_sun can be inferred from the low proper motion of Sgr A* (Backer -- this volume).

The enormous increase in observational data obtained for Sgr A* in recent years has enabled us to develop, compare and constrain a variety of models for the emission characteristics of this source. Because of its relative proximity and further observational input to come Sgr A* may therefore become one of the best laboratories for studying supermassive black hole candidates and basic AGN physics. This paper briefly summarizes our current understanding of this enigmatic radio source.

Paper: Available in PostScript and LaTex Format (Kluwer-special).

Other publications can be found here.

Questions: Heino Falcke, hfalcke@mpifr-bonn.mpg.de