Title:	On the origin of the wide HI absorption line towards Sgr A*
Authors:	Dwarakanath, K.S. Goss, W.M. Zhao, J.H. Lang, Cornelia C.
Keywords:	Galaxy Nucleus—radiolines ISM
Issue Date:	2004
Publisher:	Indian Academy of Sciences, Bangalore, India.
Citation:	Journal of Astrophysics and Astronomy, 2004, Vol. 25, p129-141.
Abstract:	We have imaged a region of ~5 extent surrounding Sgr A* in the HI 21 cm-line absorption using the Very Large Array. A Gaussian decomposition of the optical depth spectra at positions within ~2(~5 pcat 8.5 kpc) of Sgr A* detects a wide linw underlying the many narrow absorption lines. The wide line has a mean peak optical depth of 0.32 ± 0.12 centered at a mean velocity of Vlsr = -4 ± 15 km s-1. The mean full width half maximum is 119 ± 42 km s-1. Such a wide line is absent in the spectra at positions beyond ~2 from Sgr A*. The position-velocity diagrams do not reveal any diffuse feature which could be attributed to a large number of HI clouds along the line of sight to Sgr A*. Consequently, the wide line has no implications either to a global population of shocked HI clouds in the Galaxy or to the energetics of the interstellar medium as was earlier thought.
URI:	http://hdl.handle.net/2289/851
ISSN:	0250-6335
Copyright:	Indian Academy of Sciences, Bangalore, India.
Appears in Collections:	Research Papers (A&A)

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