Three-Dimensional Observations of H_2 Emission around Sgr A East - I. Structure in the Central 10 Parsecs of Our Galaxy

Abstract

We have obtained velocity-resolved spectra of the H_2 v=1-0 S(1) (lambda = 2.1218 micron) emission line at 2 arcsec angular resolution (or 0.08 pc spatial resolution) in four regions within the central 10 pc of the Galaxy where the supernova-like remnant Sgr A East is colliding with molecular clouds. To investigate the kinematic, physical, and positional relationships between the important gaseous components in the center, we compared the H_2 data cube with previously published NH_3 data. The projected interaction-boundary of Sgr A East is determined to be an ellipse with its center offset 1.5 pc from Sgr A* and dimensions of 10.8 pc X 7.6 pc. This H_2 boundary is larger than the synchrotron emission shell but consistent with the dust ring which is believed to trace the shock front of Sgr A East. Since Sgr A East is driving shocks into its nearby molecular clouds, we can determine their positional relationships using the shock directions as indicators. As a result, we suggest a revised model for the three-dimensional structure of the central 10 pc. The actual contact between Sgr A East and all of the surrounding molecular material, including the circum-nuclear disk and the southern streamer, makes the hypothesis of infall into the nucleus and feeding of Sgr A* very likely.

arXiv comment14 pages, 13 figures. Accepted for publication in Astrophysical Journal 2008 Jan 20, v673 n1. The high quality PDF file is on http://soojong.khu.ac.kr/mypaper/2008_leesh_sgrae-1.pdf

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• The Excitation of HCN and HCO+ in the Galactic Center Circumnuclear Disk
• Interstellar gas within $\sim 10$ pc of Sgr A${}^{\ast }$
• Mapping photodissociation and shocks in the vicinity of Sgr A*
• Very Large Array Observations of Galactic Center OH 1720 MHz Masers in Sagittarius A East and in the Circumnuclear Disk
• The Metal-enriched Thermal Composite Supernova Remnant Kesteven 41 (G337.8-0.1) in a Molecular Environment
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• 3-D CMZ IV: Distinguishing Near vs. Far Distances in the Galactic Center Using Spitzer and Herschel
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• High-spectral resolution M-band observations of CO Rot-Vib absorption lines towards the Galactic center
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• 3D CMZ V: A new orbital model of our Galaxy's Center, informed by data across the electromagnetic spectrum