Journal article
On the Origin of the Wide HI Absorption Line Toward Sgr A
Journal of astrophysics and astronomy, Vol.25, pp.129-141
09/2004
DOI: 10.1007/BF02702369
Abstract
We have imaged a region of about 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 about 2' (approx. 5 pc at 8.5 kpc) of
Sgr A* detects a wide line 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 V(lsr) = -4 +/- 15 km/s. The mean full width at half maximum is 119
+/- 42 km/s. Such a wide line is absent in the spectra at positions beyond
about 2' from Sgr A*. The position-velocity diagrams in optical depth reveal
that the wide line originates in various components of the circumnuclear disk
(radius approx. 1.3') surrounding Sgr A*. These components contribute to the
optical depth of the wide line in different velocity ranges. 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.
Details
- Title: Subtitle
- On the Origin of the Wide HI Absorption Line Toward Sgr A
- Creators
- K. S Dwarakanath - Raman Research InstituteW. M Goss - National Radio Astronomy ObservatoryJ. H Zhao - Center for Astrophysics Harvard & SmithsonianC. C Lang - U. Iowa
- Resource Type
- Journal article
- Publication Details
- Journal of astrophysics and astronomy, Vol.25, pp.129-141
- DOI
- 10.1007/BF02702369
- ISSN
- 0250-6335
- eISSN
- 0973-7758
- Publisher
- Springer
- Language
- English
- Date published
- 09/2004
- Academic Unit
- Liberal Arts and Science Admin; Physics and Astronomy
- Record Identifier
- 9984429049702771
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