Abstracts, Galactic Center Workshop '98
ABSTRACT

SGR A* IN THE MID-INFRARED REFERENCE FRAME: THE RELATIONSHIP BETWEEN THE RADIO AND INFRARED SOURCES IN THE CENTRAL PARSEC

Gezari, D.

NASA/Goddard Space Flight Center, Code 685, Greenbelt, MD 20771

ABSTRACT: There is growing support for the idea that a massive black hole may be located at the Galactic Center, and that the non-thermal radio continuum emission of Sgr A* results from infall of material into an accretion disc around it. Comparison of the infrared and radio source distributions can shed light on three important questions which are relevant to this issue: 1) Can the radio source Sgr A* be identified with any other source observed at any other wavelength? 2) Is there any evidence that Sgr A* directly interacts with other observed matter in the central parsec? 3) Is the relationship between the infrared and radio source distributions consistent with the idea that a massive black hole is present at the position of Sgr A*? We have independently determined the position of Sgr A* with respect to the mid-infrared sources in the central parsec by a direct correlation of our 12.4 (m image and the 2-cm continuum VLA data of Yusef-Zadeh (1996, private communication), without a priori knowledge of any other position determinations (e.g. Menten et al. 1997). The registration was achieved by an iterative process, correlating structure in the extended emission as well as the compact peaks, and relaxing all preconceptions about which sources must coincide (recognizing the possibility that some of the objects may actually be compact clusters of sources, or the radio and infred components arise from completely independent objects). The results are compared to other astrometry, and the discrepancies are investigated as possible clues to real morphological differences which could bear upon the fundamental questions posed above.

LINKS: Program, Author, gezari@stars.gsfc.nasa.gov