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