@article {Theuns:May 2002:0035-8711:367,
author = "Theuns, Tom",
author = "Zaroubi, Saleem",
author = "Kim, Tae-Sun",
author = "Tzanavaris, Panayiotis",
author = "Carswell, Robert F.",
title = "Temperature fluctuations in the intergalactic medium",
journal = "Monthly Notices of the Royal Astronomical Society",
volume = "332",
year = "May 2002",
abstract = "The temperature of the low-density intergalactic medium (IGM) is set by the balance between adiabatic cooling resulting from the expansion of the Universe , and photoheating by the ultraviolet (UV) background. We have analysed the Lyα forest of 11 high-resolution quasar spectra using wavelets, and find strong evidence of a marked jump in the temperature at the mean density, T0, of 60±14 per cent over the redshift interval z=[3.5,3.1] , which we attribute to reionization of He ii. The jump can be seen in all three of our spectra that straddle redshift 3.3, at a significance of ⩾99 per cent. Below z∼3.1 , our results are consistent with a smooth cooling down of the universe, as expected when adiabatic expansion dominates over photoheating by a UV background from quasi-stellar objects (QSOs) and galaxies. We find no evidence of thermal fluctuations on scales ⩾5000 km s−1 larger than 50 per cent, which could be detected by our method, suggesting that the IGM follows a reasonably well-defined temperature-density relation. We demonstrate that the mean wavelet amplitude 〈A〉∝1/T0 , and calibrate the relation with hydrodynamical simulations. We find T0⩾1.2×104 K at z⩾3.6 . Such high temperatures suggest that H ireionization occurred relatively recently.",
pages = "367-382(16)",
url = "http://www.ingentaconnect.com/content/bsc/mnr/2002/00000332/00000002/art00015"
doi = "doi:10.1046/j.1365-8711.2002.05316.x"
}