The Edges of Things

Author: Portas A.  

Publisher: Edp Sciences

E-ISSN: 1638-1963|56|issue|129-132

ISSN: 1633-4760

Source: EAS Publications Series, Vol.56, Iss.issue, 2012-09, pp. : 129-132

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Abstract

We investigate the radial column density distribution in a sample of 9 galaxies taken from the THINGS survey. The HI data have been used to probe the extent of the neutral (atomic) gas disks down to column densities of less than 0.1 ℳ pc−2. The size of the disks might be set simply by the amount of available gas that has contributed to the formation of the galaxy or truncated by ionisation by the extragalactic radiation field once the HI column density has dropped below a certain threshold.