Damped Lyman-alpha system
= Damped Lyman-alpha system
{title2=$N_{\rm HI}\gtrsim2\times10^{20}\,\mathrm{cm}^{-2}$}
{wiki}
A damped Lyman-alpha system has a sufficiently high neutral-hydrogen <column density> that the Lorentzian wings of its <Voigt profile> are conspicuous. These wings come from the finite lifetime of the excited atomic state, not from unusually high gas <temperature>. Damped systems usually trace substantial neutral reservoirs associated with <galaxies>.