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The kinetic temperature in a damped Lyman α absorption system in Q2206−199 – an example of the warm neutral medium




By comparing the widths of absorption lines from O i, Si ii and Fe ii in the redshift zabs= 2.076 single-component damped Lyα system in the spectrum of Q2206−199 we establish that these absorption lines arise in warm neutral medium (WNM) gas at ∼12 000 ± 3000 K. This is consistent with thermal equilibrium model estimates of ∼8000 K for the WNM in galaxies, but not with the presence of a significant cold component. It is also consistent with, but not required by, the absence of C ii fine structure absorption in this system. Some possible implications concerning abundance estimates in narrow-line WNM absorbers are discussed.