Millions of Single Cloud Weak MgII Systems
Abstract
We report on a population of absorption systems selected by the presence of very weak Mg II doublets. A sub-population of these systems are iron enriched and have near solar metallicities. This would indicated advanced stages (i.e. few Gyr) of in situ star formation within the absorbing structures. From photoionization modeling, we infer low ionization fractions of f(HI/H)~0.01, and gas densities of ~0.1 cm^-3. Since the maximum HI column densities are \~10^17 cm^-2, the inferred cloud sizes are ~10 pc. From their redshift number densities, this implies that their co-moving spatial density outnumbers normal bright galaxies by a factor of a few million.
Cite
@article{arxiv.astro-ph/0111315,
title = {Millions of Single Cloud Weak MgII Systems},
author = {Chris Churchill and Jane Rigby and Jane Charlton},
journal= {arXiv preprint arXiv:astro-ph/0111315},
year = {2007}
}
Comments
to appear in Proceedings for the XVIIth IAP Colloquium: Gaseous Matter in Galaxies and Intergalactic Space (held 19-23 June 2001)