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Title: ON THE ORIGIN OF THE CENTRAL 1'' HOLE IN THE STELLAR DISK OF SGR A* AND THE FERMI GAMMA-RAY BUBBLES

The supermassive black hole Sgr A* at the center of the Galaxy is surrounded by two misaligned disks of young, massive stars extending from ∼0.04 to 0.4 pc. The stellar surface density increases as ∼r {sup –2} toward Sgr A* but is truncated within 1'' (0.04 pc). We explore the origin of this annulus using a model in which star formation occurs in a disk of gas created through the partial capture of a gas cloud as it sweeps through the inner few parsecs of the galaxy and temporarily engulfs Sgr A*. We identify the locations within which star formation and/or accretion onto Sgr A* take place. Within 0.04 pc the disk is magnetically active and the associated heating and enhanced pressure prevents the disk from becoming self-gravitating. Instead, it forms a magneto-turbulent disk that drains onto Sgr A* in ≲ 3 × 10{sup 6} yr. Meanwhile, fragmentation of the gas beyond the central 0.04 pc hole creates the observed young stellar disk. The two large-scale bubbles of gamma-ray emission extending perpendicular to the Galactic plane may be created by a burst of accretion of ∼1 × 10{sup 5} M {sub ☉} of gas lying between 0.01 and 0.03 pc. The observed stellar ages imply thatmore » this capture event occurred ∼10{sup 6.5} yr ago, thus such events occurring over the lifetime of the Galaxy could have significantly contributed to the current mass of Sgr A* and to the inner few parsecs of the nuclear star cluster. We suggest that these events also occur in extragalactic systems.« less
Authors:
 [1] ;  [2]
  1. Department of Physics and Astronomy and Research Centre for Astronomy, Astrophysics and Astrophotonics, Macquarie University, Sydney, NSW 2109 (Australia)
  2. Department of Physics and Astronomy and Center for Interdisciplinary Exploration and Research in Astrophysics, Northwestern University, Evanston, IL 60208 (United States)
Publication Date:
OSTI Identifier:
22365833
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 787; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCRETION DISKS; BLACK HOLES; BUBBLES; CLOUDS; GAMMA RADIATION; HEATING; LIFETIME; MAGNETOHYDRODYNAMICS; MASS; MILKY WAY; STAR CLUSTERS; STAR EVOLUTION; STAR MODELS; STARS