1995/12/13 by Heino Falcke, H. Falcke, Falcke, Heino +2
Engineering · Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics (astro-ph) #FOS: Physical sciences #Mechanics and Biomechanics Studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9512092
to appear in ``Jets from Stars and Galactic Nuclei'', Springer Lecture Notes, plain TeX, 4 pages, also at http://www.astro.umd.edu/~hfalcke/publications.html
openalex publication_date 1995/12/13 · arxiv created 1995/12/14 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present a simple argument that the missing x-ray flux from the Galactic\nCenter source Sgr~A* ist not evidence it against -- as claimed by Goldwurm\net al. 1994 -- but rather indirect evidence it for the presence of a\nsupermassive black hole. The radio spectrum provides a strict it lower limit\nfor the size of Sgr~A* (R>3\⋅ 1011cm). A more compact source would be\ncompletely synchrotron self-absorbed. This size is 106 times larger than a\nstellar-mass black hole, yet the bolometric radio luminosity is comparable to\nor even larger than the x-ray luminosity where matter accreting onto a it\nstellar-mass black hole would inevitably radiate the it bulk of its\nluminosity. Hence, either the bulk of the accretion power is radiated in the UV\n(where the limits are higher), or the accretion has to stop at the radio-scale\nto avoid producing x-rays brighter than the radio emission. Both would be a\nnatural consequence of a supermasive black hole with \∼106M sun.\n