The covering factor of high redshift damped Lyman-$\alpha$ systems
Cosmology and Nongalactic Astrophysics
2011-02-11 v1
Abstract
We have used the Very Long Baseline Array to image 18 quasars with foreground damped Lyman- systems (DLAs) at 327, 610 or 1420 MHz, to measure the covering factor of each DLA at or near its redshifted HI 21cm line frequency. Including six systems from the literature, we find that none of 24 DLAs at has an exceptionally low covering factor, with for the 14 DLAs at , for the 10 systems at , and consistent covering factor distributions in the two sub-samples. The observed paucity of detections of HI 21cm absorption in high- DLAs thus cannot be explained by low covering factors and is instead likely to arise due to a larger fraction of warm HI in these absorbers.
Keywords
Cite
@article{arxiv.0903.4483,
title = {The covering factor of high redshift damped Lyman-$\alpha$ systems},
author = {N. Kanekar and W. M. Lane and E. Momjian and F. H. Briggs and J. N. Chengalur},
journal= {arXiv preprint arXiv:0903.4483},
year = {2011}
}
Comments
6 pages, 20 figures; MNRAS (Letters), in press