Magnetic spiral arms in galaxies |
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Authors: | Anvar Shukurov |
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Affiliation: | Max-Planck-Institut fu¨r Astrophysik, Postfach 1523, 85740 Garching, Germany,;Steward Observatory, University of Arizona, Tucson, AZ 85721, USA |
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Abstract: | The Doppler parameter distribution of Lyα absorption lines is calculated for a set of numerical simulations with different re-ionization histories. The differences in temperature between different re-ionization histories are as large as a factor of 3–4 depending on the spectrum of the ionizing sources and the redshift of helium re-ionization. These temperature differences result in observable differences in the Doppler parameter distribution. The best agreement with the observed Doppler parameter distribution between redshifts of 2 and 4 is found if hydrogen and helium are re-ionized simultaneously at or before a redshift of 5 with a quasar-like spectrum. |
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Keywords: | intergalactic medium quasars: absorption lines cosmology: observations cosmology: theory |
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