Year: 1999
Type: conference-paper
Abstract: The velocity profiles of weak metal absorption lines can be used to observationally probe the kinematic state of gas in damped Lyman-α systems. Prochaska and Wolfe [5] have argued that the flat distribution of velocity widths (Δv) combined with the asymmetric line profiles indicate that the DLAS are disks with large rotation velocities (∼200 km/s). An alternative explanation has been proposed by Haehnelt, Steinmetz, and Rauch (HSR) [2], in which the observed large velocity widths and asymmetric profiles can be produced by lines of sight passing through two or more clumps each having relatively small internal velocity dispersions. We investigate the plausibility of this scenario in the context of semi-analytic models based on hierarchical merging trees and including simple treatments of gas dynamics, star formation, supernova feedback, and chemical evolution. We find that all the observed properties of the metal-line systems including the distribution of Δv and the asymmetric profiles, can be reproduced by lines of sight passing through sub-clumps that are bound within larger virialized dark matter halos. In order to produce enough multiple hits, we find that the cold gas must be considerably more extended than the optical radius of the proto-galaxies, perhaps even beyond the tidal radius of the sub-halo. This could occur due to tidal stripping or supernova-driven outflows.
DOI: 10.1063/1.58642
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2951758124