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 z_abs= 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.