Simona Gallerani Constraining cosmic reionization models with QSOs, GRBs and LAEs observational data...
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Transcript of Simona Gallerani Constraining cosmic reionization models with QSOs, GRBs and LAEs observational data...
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