Temperature fluctuations in the intergalactic medium
| Autor: | Tom Theuns, Robert F. Carswell, Saleem Zaroubi, Tae-Sun Kim, Panayiotis Tzanavaris |
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| Rok vydání: | 2002 |
| Předmět: |
QSOS
Physics Astrophysics (astro-ph) FOS: Physical sciences Thermal fluctuations Astronomy and Astrophysics Quasar Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics Galaxy Redshift Metric expansion of space Space and Planetary Science Adiabatic process Reionization Astrophysics::Galaxy Astrophysics |
| Zdroj: | Monthly notices of the Royal Astronomical Society |
| ISSN: | 1365-2966 0035-8711 |
| Popis: | The temperature of the low-density intergalactic medium is set by the balance between adiabatic cooling resulting from the expansion of the universe, and photo-heating by the UV-background. We have analysed the Lyman-alpha forest of eleven high-resolution quasar spectra using wavelets, and find strong evidence of a marked jump in the temperature at the mean density, T_0, of 60 per cent around a redshift z=3.3, which we attribute to reionization of HeliumII. 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 photo-heating by a UV-background from QSOs and galaxies. We find no evidence of thermal fluctuations on scales greater than 5000 km/s 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 scales inversely with T_0 and calibrate the relation with hydrodynamical simulations. We find T_0= 12000K at z>3.6. Such high temperature suggest that Hydrogen reionization occured relatively recent. 17 pages, minor changes, MNRAS published version |
| Databáze: | OpenAIRE |
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