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

HI

HIIHII

HI

Pre-overlap stage

HII

Overlap stage Post-overlap stage

HII

HII

HIHI

HII

Reionization: a phase transition in the early Universe

Dark agesR

O

E

What is the epoch of reionization (EOR)?

?6 z

~500 kyr ~100 Myr ≤1 Gyr

z~1000 z~6z~20

Reionization process: observational constraints

Quasars

CMB11reiz

Gamma Ray Bursts

Ly Emitters

Page et al. (2007)

Komatsu et al. (2009)

Becker et al. (2003)

QSOs constraints on cosmic reionization

SDSS

~20 QSOs

@ 5.7<z<6.4

6~reiz

Fan et al. (2005)

GRBs constraints on cosmic reionization

MODELLING

DLA system

Neutral IGM{

Transmission feature around the Ly line

GRB 050904 @ z = 6.3

SUBARU TELESCOPE

2.0

0.0

HI

bestfitHI

x

x3.6reiz

(Totani et al. 2005)

(Tagliaferri et al. 2005)

(Kashikawa et al. 2006)

SUBARU DEEP FIELD

LAEs @ z=6.6

LAEs constraints on cosmic reionization

LAEs @ z=5.7

VS

No evolution LFUV

for 5.7<z<6.6

No evolution LFLyα

for 3<z<6 6.6reiz

Modeling reionization

Choudhury & Ferrara (2005/2006); Choudhury, Ferrara & SG (2008)

Free parameters: SFPopIII

SFPopII ,

escPopIII

escPopII ff ,

Log-Normal model QSOs, PopII, PopIII

Reionization models

Photo-Ionization Rate

ERMLRM

Data from McDonald & Miralda-Escude’(2001); Bolton et al. (2007); Fan et al.(2006)

Early Reionization (ERM)

7reionzHII

Highly ionized IGM at z=6

Late Reionization (LRM)

6reionz

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(TIGM; UVB)

(Voigt profile)

SG, Choudhury & Ferrara (2006)

Simulated spectra

ERMLRM

Optical depth evolution

Fan et al. (2006)

Songaila (2004)

GAPSGAPS

3.67.5 z

SG, C

houd

hury

& F

erra

ra (

2006

)

Largest gap width distributionObservations vs Simulations

5106 HIx5104 HIx

6.5z3.5z

xHI<0.36 @ z=6.3

Low Redshift (zem<6) High Redshift (zem>6)

SG, F

errara, Fan, C

houdhury (2007)

ERMLRM

ERMLRM

GRBs absorption spectra

Kawai et al. (2006)

52 Å

GRB050904 @ z=6.3

Tagliaferri et al. (2005)

142 Å

GRBs absorption spectra

Kawai et al. (2006)GRB050904 @ z=6.3

Tagliaferri et al. (2005)

190 Å

GRBs absorption spectra

Kawai et al. (2006)GRB050904 @ z=6.3

Tagliaferri et al. (2005)

Largest gap probability isocontours: GRBs SG

, Sal

vate

rra,

Fer

rara

, Cho

udhu

ry (

2007

)

The ERM is twice more probable wrt the LRM

The gap sizes are consistent with xHI=6.410-

3.

5%

5%

10%

10%

40%40%

0

Lα[1

042er

g/se

c]

14

12

10

8

4

6

2

obs

91209040 9180

intL

obsL

xHI=1e-3xHI=0.05xHI=0.1

fesc =

0.1; SF

R=

113 Msun /yr; t* =

1.e8 yr

Dayal, Ferrara, SG (2008)

z f*/εDC fesc,α

4.5 3.5 0.075

5.7 3.5 0.3

6.6 3.5 0.3

z Mh (Msun) SFR(Msun/yr)

4.5 1011.1-12.5 6-160

5.7 1010.8-12.3 3-103

6.6 1010.7-12.0 2-43

Log Lα[erg/sec]

Log

N (

>L

α )

[Mpc

-3]

42.5 43 43.5

-5.5

-4.5

-3.5

-2.5

42

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 IGM @ z~6.

• The gap size along the LOS towards the GRB050904 @ z=6.3 is consistent with xHI ~10-3.

• The evolution of the Lyα luminosity function @ 5.7<z<6.6 is well fitted by a reionization model with zrei ≥ 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 distributionObservations vs Simulations

Low Redshift (zem<6)

ERM LRM

SG, F

erra

ra, F

an, C

houd

hury

(20

07)

High Redshift (zem>6)

LRM

ERM

6.5z3.5z

5108 HIx6.5z

HR

Fan et al. (2006

This work

0

Lα[1

042er

g/se

c]

14

12

10

8

4

6

2

Lyα emitting galaxies

obs

91209040 9180

hffQL esc )1(3

2int

hm

b

HDC

Mt

fSFR

1*

intL

obsL

fesc fraction of ionizing photons that escape the galaxy

fα fraction of Lyα photons that escape the galaxy

Q ionizing photons rate

f* fraction of baryonic matter which forms stars over a timescale t*=εDCtH

eLLobs int

xHI=1e-3xHI=0.05xHI=0.1

fesc =

0.1; SF

R=

113 Msun /yr; t* =

1.e8 yr