| The Amplitude of Mass Density Fluctuations At (2007) | |||||||||||||
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| The real-space optical depth distribution along the line of sight to the QSO Q1422+231 is recovered from two HIRES spectra using a modified version of the inversion method proposed by Nusser & Haehnelt (1999). The first two moments of the truncated optical depth distribution are used to constrain the density fluctuation amplitude of the intergalactic medium (IGM) assuming that the IGM is photoionized by a metagalactic UV background and obeys a temperature-density relation. The fluctuation amplitude and the power law index ff of the relation between gas and neutral hydrogen (HI) density are degenerate. The rms of the IGM density at z 3:25 estimated from the first spectrum is oe = p exp [(1:8 \Sigma 0:27) 2 =ff 2 ] \Gamma 1, with 1:56 ! ff ! 2 for plausible reionization histories. This corresponds to 0:9 ! oe ! 2:1 with oe(ff = 1:7) = 1:44 \Sigma 0:3. The values obtained from the second spectrum are higher by 20%. If the IGM density traces the dark matter (DM) as suggested by... | |||||||||||||
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