21cm Constraints on Reionization Benedetta Ciardi MPA T. Di Matteo (CMU), A. Ferrara (SISSA), I. Iliev (CITA), P. Madau (UCSC), selli (MPA), F. Miniati (ETH), R. Salvaterra (UInsubria), E. Scannapieco (UC P. Shapiro (UAustin), F. Stoehr (IAU), M. Valdes (SISSA), S. White (MPA)
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21cm Constraints on Reionization Benedetta Ciardi MPA T. Di Matteo (CMU), A. Ferrara (SISSA), I. Iliev (CITA), P. Madau (UCSC), A. Maselli (MPA), F. Miniati.
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21cm Constraints on
Reionization
Benedetta CiardiMPA
T. Di Matteo (CMU), A. Ferrara (SISSA), I. Iliev (CITA), P. Madau (UCSC), A. Maselli (MPA), F. Miniati (ETH), R. Salvaterra (UInsubria), E. Scannapieco (UCSB),
P. Shapiro (UAustin), F. Stoehr (IAU), M. Valdes (SISSA), S. White (MPA)
The gas needs to cool to beavailable for star formation
The first sites of ionizing radiation
KTvir410
KTvir410
Atomic hydrogen cooling
Molecular hydrogen cooling
DM halos virial temperature Cooling function (no metals!)
Temperature [K]
Λ/n
² [e
rg c
m³/
s]
H2 cooling
Atomic H cooling
HD coolingTem
pera
ture
[K
]
1-σ
2-σ
3-σ
(Barka
na &
Loeb
20
01
)
Redshift
H2 is a key species in the early universe
Feedback effects on primordial objects
The first generation of stars affects the subsequent star formation process
Radiative feedback
Mechanical feedback
Chemical feedback
H2 photodissociation(L-W photons, 11.2-13.6 eV)
Radiative feedback
Photoheating
(Gn
ed
in 2
00
0)
Photoevaporation
(Sh
ap
iro e
t al. 2
00
3)
Feedback effects on primordial objects
Blowout/blowaway
Blow-awayBlow-out
(Mac Lo
w &
Ferra
ra 9
9)
Radiative feedback
Mechanical feedback
Chemical feedback
Mechanical feedback
Feedback effects on primordial objects
Change in fragmentation mode due to ZRadiative feedback
Mechanical feedback
Chemical feedbackChemical feedback~ 100 Msun
~ 1 Msun
~ 0.1 Msun
F rac t
ion
of
meta
ls d
ep
lete
d o
nto
du
s t g
r ain
s
Metallicity / Solar Metallicity
(Sch
neid
er e
t al)
(Bromm et al, Schneider et al)
Feedback effects on primordial objects
Radiative feedback
Mechanical feedback
Chemical feedback
IGM reionization
See Ciardi & Ferrara 2005 for a review
Constraints on the epoch of reionization
High-z QSOs latest stages of reionization at z~6
CMB global amount of electrons
Which are the first sources of ionizing radiation?How did the reionization process evolve?
Which is its interplay with the galaxy formation process?
21 cm line diagnostic
21 cm
T S CMBT
Ideal probe of neutral H at high-zdifferent observed frqs. different z
(ν~150,120,80 MHz z~8,11,18)
DECOUPLING
HI ground state
)s0.07K/T3exp(l/nun
• CMB photons are absorbed by HI thermal equilibrium
u
l
Scattering with Lyalpha photons emitted by the same stars that reionize