Paper: astro-ph/0512211
Date: Thu, 8 Dec 2005 01:21:59 GMT (429kb)

Title: On The Nature of the Compact Dark Mass at the Galactic Center

Authors: Avery E. Broderick (1) and Ramesh Narayan (1,2) ((1) Institute for
Theory and Computation, (2) Harvard University)

Comments: 6 pages, 2 figures, submitted to ApJ Letters
\\
We consider a model in which Sgr A*, the 3.5x10^6 M_sun supermassive black
hole candidate at the Galactic Center, is a compact object with a surface.
Given the very low quiescent luminosity of Sgr A* in the near infrared, the
existence of a hard surface, even in the limit in which the radius approaches
the horizon, places severe constraints upon the steady mass accretion rate in
the source, requiring dM/dt < 10^-12 M_sun/yr. This limit is well below the
minimum accretion rate needed to power the observed submillimeter luminosity of
Sgr A*. We thus argue that Sgr A* does not have a surface, i.e., it must have
an event horizon. The argument could be made more restrictive by an order of
magnitude with microarcsecond resolution imaging, e.g., with submillimeter
VLBI.

\\ ( http://arXiv.org/abs/astro-ph/0512211 , 429kb)