GREEN BANK TELESCOPE OBSERVATIONS OF LOW COLUMN DENSITY HI AROUND NGC 2997 AND NGC 6946

As a first attempt to identify such cold flows around nearby galaxies and complete the census of HI down to N sub(HI) ~ 10 super(18) cm super(-2), I used the Robert C. Byrd Green Bank Telescope (GBT) to map the circumgalactic (r [lap] 100-200 kpc) HI environment around NGC 2997 and NGC 6946. The res...

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Bibliographic Details
Published in:The Astronomical journal 2014-03, Vol.147 (3), p.1-8
Main Author: Pisano, D J
Format: Article
Language:English
Subjects:
Astronomical instruments
Banks
Census
Complement
Density
Disks
Galaxies
Satellites
Telescopes
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Summary:As a first attempt to identify such cold flows around nearby galaxies and complete the census of HI down to N sub(HI) ~ 10 super(18) cm super(-2), I used the Robert C. Byrd Green Bank Telescope (GBT) to map the circumgalactic (r [lap] 100-200 kpc) HI environment around NGC 2997 and NGC 6946. The resulting GBT observations cover a 4 deg super(2) area around each galaxy with a 5[sigma] detection limit of N sub(HI) ~ 10 super(18) cm super(-2) over a 20 kms super(-1) line width. This project complements absorption line studies, which are well-suited to the regime of lower N sub(HI). Around NGC 2997, the GBT HI data reveal an extended HI disk and all of its surrounding gas-rich satellite galaxies, but no filamentary features. After correcting for resolution differences, the HI extent of the galaxy is 23% larger at the N sub(HI) = 1.2 x 10 super(18) cm super(-2) level as measured by the GBT.
ISSN:0004-6256
1538-3881
DOI:10.1088/0004-6256/147/3/48