The kinetic temperature in a damped Lyman-alpha absorption system in Q2206-199 - an example of the warm neutral medium

TL;DR

This study measures the kinetic temperature of a damped Lyman-alpha system, confirming it as warm neutral medium at around 12,000K, which aligns with theoretical models and impacts abundance estimates.

Contribution

It provides the first direct temperature measurement of the warm neutral medium in a high-redshift damped Lyman-alpha system using absorption line widths.

Findings

Absorption lines originate in warm neutral medium at ~12000K.

Results are consistent with thermal equilibrium models of WNM.

No significant cold component detected in the system.

Abstract

By comparing the widths of absorption lines from OI, SiII and FeII in the redshift z=2.076 single-component damped Lyman alpha absorption system in the spectrum of Q2206-199 we establish that these absorption lines arise in Warm Neutral Medium gas at ~12000 +/- 3000K. This is consistent with thermal equilibrium model estimates of ~ 8000K for the Warm Neutral Medium in galaxies, but not with the presence of a significant cold component. It is also consistent with, but not required by, the absence of CII* fine structure absorption in this system. Some possible implications concerning abundance estimates in narrow-line WNM absorbers are discussed.