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.
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A Damped Lyman-alpha system (DLA) is a type of astronomical object observed in the spectra of distant quasars and galaxies. It is characterized by a strong absorption feature in the Lyman-alpha transition of hydrogen (at a wavelength of 121.6 nm) due to neutral hydrogen gas in the intervening medium.