XXIVth IAP Colloquium

Far away : light in the young universe at redshift beyond three

Monday July 7 to Friday July 11, 2008

List of GALLERANI's Presentation(s) ( Updated 20/01/2011 12:01:47 )

Precise if your presentation is oral or a poster : Poster
Title of your presentation : Looking for reionization tracks in the young Universe

I will present a cosmic reionization scenario which simultaneously accounts for quasars, Gamma Ray Bursts and Lyman Alpha Emitters observational data.

We have built up a semi-analytical model of the Lyalpha forest which fits most of the observational properties of QSOs absorption spectra at 3< z <6. By comparing our simulations with a sample of 17 QSOs spectra at 5.7< zem <6.4 we constrain the neutral hydrogen fraction xHI at these epochs, finding that it evolves smoothly from 10^{-4.4} at z=5.3 to 10^{-4.2} at z=5.6, with a robust upper limit xHI<0.36 at z=6.3.

This conclusion is confirmed by analyzing the optical afterglow spectrum of the GRB050904 detected at zem=6.3, whose spectral features are consistent with a highly ionized (xHI~10^{-4.0}) intergalactic medium along that line of sight.

The model, calibrated to match QSOs and GRBs data, is also successful in explaining the Luminosity Function of LAEs at 4.5< zem <6.6.

The overall result points towards an extended reionization process which starts at z>=11 and completes at z>=7, in agreement with the recent WMAP5 data.

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