Journal Article

The thermal history of the intergalactic medium

Joop Schaye, Tom Theuns, Michael Rauch, George Efstathiou and Wallace L.W. Sargent

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 318, issue 3, pages 817-826
Published in print November 2000 | ISSN: 0035-8711
Published online November 2000 | e-ISSN: 1365-2966 | DOI:
The thermal history of the intergalactic medium⋆

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At redshifts z ≳ 2, most of the baryons reside in the smooth intergalactic medium which is responsible for the low column density Lyα forest. This photoheated gas follows a tight temperature-density relation which introduces a cut-off in the distribution of widths of the Lyα 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 ratio quasar spectra and determined the thermal evolution of the intergalactic medium in the redshift range 2.0–4.5. At a 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 He ii.

Keywords: intergalactic medium; quasars: absorption lines; cosmology: miscellaneous

Journal Article.  0 words. 

Subjects: Astronomy and Astrophysics

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