Simona Gallerani Constraining cosmic reionization models with QSOs, GRBs and LAEs observational data In collaboration with: A. Ferrara, X. Fan, T. Choudhury, R. Salvaterra, P. Dayal Astronomical Observatory of Rome

Pre-overlap stage Overlap stage Post-overlap stage Reionization: a phase transition in the early Universe Dark ages What is the epoch of reionization (EOR)? ~500 kyr~100 Myr≤1 Gyr z~1000z~6z~20

Reionization process: observational constraints Quasars CMB Gamma Ray Bursts Ly  Emitters Page et al. (2007) Komatsu et al. (2009)

Becker et al. (2003) QSOs constraints on cosmic reionization SDSS ~20 5.7<z<6.4 Fan et al. (2005)

GRBs constraints on cosmic reionization  MODELLING DLA system Neutral IGM { Transmission feature around the Ly  line GRB z = 6.3 SUBARU TELESCOPE (Totani et al. 2005) (Tagliaferri et al. 2005)

(Kashikawa et al. 2006) SUBARU DEEP FIELD z=6.6 LAEs constraints on cosmic reionization z=5.7 VS No evolution LF UV for 5.7<z<6.6 No evolution LF Ly α for 3<z<6

Modeling reionization Choudhury & Ferrara (2005/2006); Choudhury, Ferrara & SG (2008) Free parameters: Log-Normal modelQSOs, PopII, PopIII

Reionization models Photo-Ionization Rate ERM LRM Data from McDonald & Miralda-Escude’(2001); Bolton et al. (2007); Fan et al.(2006) Early Reionization (ERM) Highly ionized IGM at z=6 Late Reionization (LRM) Two-phase IGM at z>6

Simulating the Ly  forest Coles & Jones (1991) Log-Normal model Reionization model Choudhury & Ferrara (2006) Optical depth Density field (ΛCDM) Neutral hydrogen (T IGM ; UVB) (Voigt profile) SG, Choudhury & Ferrara (2006)

Simulated spectra ERM LRM Optical depth evolution Fan et al. (2006) Songaila (2004) GAPS SG, Choudhury & Ferrara (2006)

Largest gap width distribution Observations vs Simulations x HI < z= 6.3 Low Redshift (z em <6)High Redshift (z em >6) SG, Ferrara, Fan, Choudhury (2007) ERM LRM ERM LRM

GRBs absorption spectra Kawai et al. (2006) 52 Å z=6.3 Tagliaferri et al. (2005)

142 Å GRBs absorption spectra Kawai et al. z=6.3 Tagliaferri et al. (2005)

190 Å GRBs absorption spectra Kawai et al. z=6.3 Tagliaferri et al. (2005)

Largest gap probability isocontours: GRBs SG, Salvaterra, Ferrara, Choudhury (2007) The ERM is twice more probable wrt the LRM The gap sizes are consistent with x HI =6.4  % 10% 40%

0 L α [10 42 erg/sec] obs x HI =1e-3 x HI =0.05 x HI =0.1 f esc =0.1; SFR=113 M sun /yr; t * =1.e8 yr Dayal, Ferrara, SG (2008) zf * /ε DC f esc,α zM h (M sun )SFR(M sun/yr ) Log L α [erg/sec] Log N (>L α ) [Mpc -3 ] LAEs constraints on cosmic reionization Kashikawa et al 06 Shimazaku et al 06 Dawson et al 07

An Early Reionization Model (ERM) The analysis of dark regions (gaps) in QSO absorption spectra favors a highly ionized z~6. The gap size along the LOS towards the z=6.3 is consistent with x HI ~ The evolution of the Ly α luminosity 5.7<z<6.6 is well fitted by a reionization model with z rei ≥ 7. The overall result points towards an extended reionization process which starts at z>=11 and completes at z>=7, in agreement with WMAP5 data.

Largest gap width distribution Observations vs Simulations Low Redshift (z em <6) ERM LRM SG, Ferrara, Fan, Choudhury (2007) High Redshift (z em >6) LRM ERM HR Fan et al. (2006 This work

0 L α [10 42 erg/sec] Lyα emitting galaxies obs f esc fraction of ionizing photons that escape the galaxy f α fraction of Ly α photons that escape the galaxy Q ionizing photons rate f * fraction of baryonic matter which forms stars over a timescale t * =ε DC t H x HI =1e-3 x HI =0.05 x HI =0.1 f esc =0.1; SFR=113 M sun /yr; t * =1.e8 yr