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The thermal history of the intergalactic medium

Joop Schaye·Tom Theuns·Michael Rauch·George Efstathiou·Wallace L. W. Sargent
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Abstract

At redshifts z >~ 2, most of the baryons reside in the smooth intergalactic medium which is responsible for the low column density Lyman-alpha forest. This photoheated gas follows a tight temperature-density relation which introduces a cut-off in the distribution of widths of the Lyman-alpha absorption lines (b-parameters) as a function of column density. We have measured this cut-off in a sample of nine high resolution, high signal-to-noise quasar spectra, and determined the thermal evolution of the intergalactic medium in the redshift range 2.0-4.5. At redshift z ~ 3, the temperature at the mean density shows a peak and the gas becomes nearly isothermal. We interpret this as evidence for the reionization of HeII.

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Joop Schaye, Tom Theuns, Michael Rauch, George Efstathiou, Wallace L. W. Sargent. 2000-06-13. The thermal history of the intergalactic medium. https://doi.org/10.1046/j.1365-8711.2000.03815.x

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