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First galaxies and reionization of
the Universe:
current status and problems
A. Doroshkevich
Astro-Space Center, FIAN, Moscow.
Theoretical expectations and
observational problems
• Scientific activity: >17 publications in 2012
• z~25 – 10 - formation of the first stars
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and ionizing bubbles
Bubble model, UV-background,
non homogeneities in xH and Tg
z~ 10 WMAP: τT~0.1, xH=nH/nb << 1
z~6.5 – 5 - high ionization, xH~10-3
z< 3
- xH~10-5
• 1. We do not see any manifestations of the first stars
• 2. We do not know the main sources of ionizing UV
radiation
Universe Today 12.12.2012
Possible sources of ionizing UV
background
1. exotic sources – antimatter, unstable particles,
etc…
2. First stars Pop III with Zmet<10-5 Z¤ or
3. non thermal sources - AGNs and Black Holes
4. Quasars at z < 3.5, He III
Reionisation
• Θ(z)=α(T)n(z)H(z)~3T4-0.7z103/2, T4~2.
• For z10>1 recombination becomes important !
Thermal sources: E~7MeV/baryon, Nγ< 5 105 /baryon
Non thermal sources - AGNs and Black Hole
E~ 50MeV/baryon, Nγ~3.5 106 /baryon
b N b
b
 7 N b 5 10

 0.8 10
f esc N 
f esc N  0.04
5
 rei
• fesc~ 0.1 - 0.02, Nbγ~1 - 2
Ωmet~2 10-6Ωbar~8 10-8, Ωbh~3 10-7Ωbar~ 10-8
In reality both sources are important.
Labbe I., 2010,ApJ.,708,L26, 1209.3037
• Spitzer photometry
• Z~8, 63 candidats,
• 20 actually detected
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SMD for M<-18
ρ*(z=8)~106Ms/Mpc3
Ω*(z=8)~0.4 10-5
Ωmet(z=8)~0.4 10-7
Ωreio~10-7 – 10-8
z~2.5,
Ωmet~2.3 10-6 for IGM,
Ωmet~3 10-5 for galaxies
Universe Today 1211.6804
Ellis et al. arXiv1211.6804
Three steps of galaxy formation
• 1. Formation of the virialized relaxed massive DM
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cloud (perhaps, anisotropic) at z<zrec~103 with
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ρcl ~200<ρ(z)> and overdensity δDM~104 z107M91/2
• 2. Cooling and dissipative compression of the baryonic
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component, but the bulk motions and the kinetic
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temperature of stars are preserved
• 3. Formation of stars – luminous matter with M>MJ
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Main Problem of the star formation
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MJ/M¤~2·107T43/2nb-1/2,
• For stars: T4~10-2, nb>102cm-3 , MJ/M¤<103
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z=zrec,T4~0.3, nb~250 cm-3, MJ/M¤ ~2·105
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Parameters of baryonic components
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<ρbar>~4·10-28z103g/cm3, <ρgal>~10-24g/cm3,
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<ρstar>~1 g/cm3, ρBH~2 M8-2g/cm3
• Cooling factors: H2 molecules and metals (dust, C I etc.)
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Simulations (2001)
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The box ~1Mpc, 128 -256 cells,
Ndm~107, mdm~30M0, Mgal~106 – 107 M0
Very useful general presentation
(the galaxy and star formation are possible)
Restrictions:
a. small box → random regions (void or wall) &
unknown small representativity
• b. large mass DM particles in comparison with
the mass of stars.
What is mostly interesting
• a. realization – it is possible!
• b. wide statistics of objects -- what is possible
for various redshifts
• c. rough characteristics of internal structure of
the first galaxies
• d. general quantitative analysis of main physical
processes
Density – temperature 2001
Machacek et el. 2001, ApJ, 548, 509
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M~5 105Ms
T4~0.3
nb~10cm-3
fH2~3 10-5
j21~1
MJ(25)~104Ms
MJ(20)~500Ms
• Lazy evolution,
• Monolitic object
• Monotonic growth
ρ(z)??? Instabilities!
ρ, T & Z, Wise 1011.2632
• Formation of massive galaxies owing to the merging of low mass
galaxies.
Influence of the LW background
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Actual limit is JLW21~1 – 0.1 for various redshifts
For the period of full ionization z~10 we get
JLW 21~4 Nbγ
This means that at at 10>z>8.5
the H2 molecules are practically destroyed and
star formation is strongly suppressed
• This background is mainly disappeared at z~8.5
Safranek-Shrader, 1205.3835
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Corrections
for both limits
~10 times
J21~4Nbγ
UV-background from BH accretion
• T4~1 – 4, for sources with Eg~10eV and Eg~50eV.
and depends upon cooling factors
(radiative and expansion)
Elvert:
Ne
 6.3T4 10( 4T4 7 ) / T4
N HI
• In the case we can use
New semi analytical approach
We know the process of the DM halo formation
and can use this information
• Assumptions:
• a. what is the moment of halo formation
• b. baryons follow to DM and have the same
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pressure and kinetic temperature
• c. what is the cooling of the baryonic
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components
• d. thermal instability leads to formation of
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stars with masses Mst > MJeans
Physical model
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Two steps of the DM halo formation
We consider the homogeneous ball with mass
M=109Mo M9
within the expanded Universe. Its evolution can
be described analytically up to the collapse at
1+z=10zf
and subsequent relaxation. In the case we have
for the NFW profiles two parametric description:
ρDM~10-23g/cm3M91/2zf10,
TDM~40eV M95/6zf10/3mDM/mb
and all other characteristics.
Analytical characteristics for DM component
• For the NFW halo with the virial
• mass M=109 M9 Ms formed at zf=(1+z)/10
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Within central core with r< rs we have
ρDM~10-23g/cm3M91/2zf10, TDM~40eV M95/6zf10/3mDM/mb
Cooling factors: H2 and atomic for T4>1,
Three regimes of the gas evolution –
slack, rapid and isothermal
Thermal instability and the core formation
Stars are formed for Tbar<100K and nbar>100cm-3
• with Mstar > MJ ~5 107T43/2/nbar1/2Ms
Formation of the first stars
with Mcl/M0 = 3 105 and 7 105, zf=24 (left)
and Mcl/M0=0.7 108 and 3 108, zf=11 (right)
Low mass limit for the rapid-lazy
formation of the first galaies
Behroozi et al., 1207.6105 Stellar mass vs. host halos
Small fraction of stars
Behroozi et al., 1209.3013 - SFR(Mh)
• SMF~Mh-4/3, M>Mch; SMF~Mh2/3, M<Mch (left panel)
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Ms/Mh<2 – 3% at all z! ?continual evolution?
comments
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Stars occupy very small matter fraction ?
Low massive objects dominate at all redshifts?
Is this impact of nature or selection effect?
Formation of the massive galaxies owing to the
merging of satellites with stars??
Illingworth 1977 for 13 E-galaxies
Fraction of massive objects increases more rapidly –
merging of satellites or other factors??
• Small scale perturbations and missing satellite
problem – when and where had been formed dwarf
galaxies.
Physical model
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ρDM~10-23g/cm3M91/2zf10,
TDM~40eV M95/6zf10/3mDM/mb
rs=2.3M131/6/zf10/3kpc=0.16M61/6/zf10/3kpc
Zf=0.55σv0.1/rs1/4≈0.27M13-0.1≈1.33M6-0.1
Problems of the measurements – T(r) and
dynamical masses, finally:
rs~M61/2, T~M61/2
10 clusters of galaxies
Pointecouteau et al., A&A,435, 1, 2005 ,Pratt et al., A&A 446,429
name
z
R
+/T
+/- M13 +/M/TR
1+z
Mpc
keV
10^13M_o
A1983
0.0442 0.717 0.110 2.2 0.1 10.90 0.34 0.95E+00 2.05
A2717
0.0498 0.668 0.076 2.6 0.1 8.80 0.23 0.70E+00 2.27
MKW9
0.0382 0.717 0.036
2.4 0.2 11.00 0.11 0.86E+00 2.11
A1991
0.0586 0.737 0.034 2.7 0.1 12.00 0.10 0.82E+00 2.13
A2597
0.0852 0.897 0.032 3.7 0.1 22.20 0.10 0.92E+00 2.00
A1068
0.1375 1.060 0.025 4.7 0.1 38.70 0.07 0.11E+01 1.88
A1413
0.1430 1.129 0.029 6.6 0.1 48.20 0.09 0.88E+00 1.97
A478
0.0881 1.348 0.047 7.1 0.1 75.70 0.15 0.11E+01 1.79
PKS 0745 0.1028 1.323 0.034 8.0 0.3 72.70 0.10 0.94E+00 1.88
A2204
0.1523 1.365 0.032 8.3 0.2 83.90 0.10 0.10E+01 1.83
mns
0.92E+00
sig
0.11E+00
Walker et. al, 2009, ApJ, 704, 1274 - 28 objects
name
sig_v +/Mhalf
+/- <rho> +/M*zf^10 z_f
+/km/s
10^6M_o
M_o/pc^3
Carina
6.60 1.20 3.40 1.40 0.320 0.120 0.18
0.12E01 0.53
Draco
9.10 1.20 11.00 3.00 0.230 0.060 0.23
0.11E01 0.32
Fornax 11.70 0.90 27.00 0.50 0.160 0.030 0.25
0.99E00 0.04
LeoI
9.20 1.40 6.50 2.10 0.660 0.210 0.50
0.12E01 0.44
LeoII
6.60 0.70 3.10 0.90 0.400 0.120 0.21
0.12E01 0.39
Sculptor 9.20 1.10 4.60 1.70 1.300 0.500 0.83
0.13E01 0.55
Sextant
7.90 1.30 11.00 4.00 0.100 0.030 0.99
0.99E00 0.39
UMi
9.50 1.20 7.80 2.20 0.550 0.150 0.46
0.12E01 0.37
CVen I
7.60 0.40 19.00 2.00 0.025 0.003 0.32
0.84E00 0.10
Coma
4.60 0.80 0.90 0.35 0.490 0.180 0.14
0.13E01 0.56
Hercules 3.70 0.90 2.60 1.40 0.017 0.009 0.82
0.89E00 0.53
Leo T
7.50 1.60 5.80 2.80 0.250 0.120 0.18
0.11E01 0.59
Segue 1
4.30 1.20
0.31 0.19 3.010 0.800 0.50
0.17E01 1.06
UMa I
11.90 3.50 26.10 6.00 0.200 0.120 0.30
0.10E01 0.29
UMa II
5.70 1.40
2.60 1.40 0.230 0.120 0.11
0.12E01 0.68
AndII
9.30 2.70 62.00 36.00 0.008 0.005 0.19
0.71E01 0.45
Cetus
17.00 2.00 99.00 23.00 0.110 0.020 0.32
0.90E00 0.22
Sgr^c
11.40 0.70 120.00 60.00 0.008 0.001 0.24
0.68E00 0.35
Tucana
15.80 3.60 40.00 19.00 0.460 0.220 0.86E 0.11E01 0.57
Bootes 1
6.50 2.00
5.90 3.70 0.100 0.060 0.73E 0.10E01 0.70
Cven II
4.60 1.00
0.90 0.40 0.530 0.250 0.15E 0.13E01 0.65
Leo IV
3.30 1.70
0.73 0.73 0.110 0.110 0.28E 0.11E01 1.26
Leo V
2.40 1.90
0.14 0.14 0.450 0.450 0.51E 0.14E01 1.57
Segue 2
3.40 1.80
0.23 0.23 1.310 0.300 0.19E 0.16E01 1.59
AndIX
6.80 2.50 14.00 11.00 0.023 0.017 0.26E 0.84E00 0.73
AndXV
11.00 6.00 19.00 2.00 0.230 0.250 0.30E 0.10E01 0.22
mns
0.23E
sig
0.23E
zf & zfM60.1 for 28 dSph galaxies
The
Theend
end
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Behroosi et al. 1209.3013
Comments
• Importance – instead of the experiment
• Complexity, representativity and precision
(WMAP).
• Modern facilities
• Our attempts – simulations versus analysis
Cooling functions.
Smith, B.,2008, MNRAS, 385, 1443
SN explosions
• W=GM2/Rvir~3·1055z10M95/3erg
• ESN~1052 – 1055 erg
• Dex<0.2 – 0.5 Mpc - IGM impact
• For M9>0.1 we have SN metal enrichment
• within galaxy, otherwise – matter ejection
• Low massive stars, satellites and merging
Bradley L., 1204.3641,
UV luminosity function for z~8
• Low massive
objects dominate
• Why?
• Is this selection
effect?
• What about object
collections?
suppression of object
formation ?
• What is at z=9? 10?
Tollerud et al. 2008, ApJ, 688, 277
• Observations
of the Milky
Way satellites
with different
corrections
16 observed dSph galaxies
(Walker et al.2009)
dominated by DM component
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DM parameters
ρ~0.07M61/2f3(M6)
P~37f4(M6)
S~14M60.83/f(M6)
Z10=0.9M6-0.1
• Bovill & Ricotti,
• 2009, ApJ, 693,1859
• Tollerud et al. 2008
Conclusions
• We do not see any manifestations of
the first stars
• We do not know the main sources of ionizing
UV radiation
• A. It seems that first stars Pop II & III , SNs, GRBs
are approximately effective (~30 – 40%)
• B. non thermal sources BHs remnants and/or
AGNs are more effective (~50% + ?)
• C. We can semi analytically describe the formation
and evolution of the first galaxies
Galaxies and BHs
BHs are observed in~1% of all galaxies, n~10-4Mpc-3
• Very massive BHs are observed as QSRs with
• Nqsr~10-5 – 10-6 Mpc-3 at z<5; mainly at z~2 – 2.5
• Perhaps, there are AGNs in 70% of old
massive galaxies.
• ρBH~3 10-2M9-2g/cm3,
• ρDM~10-23zf10M90.5g/cm3 within halo
Vestergaard et al. 2008
BH-distributions: M(z) & L/Led
Vestergaard, Osmer, 2009, ApJ,699,800
Number density of the SMBH,
Kelly et al., 2011, 1006.3561
BH evolution
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1. We see rare supermassive BH at z<2
- early formation and short lifetime.
2. Impact of the accretion rate.
3. Are the SMBH primordial?
4. van den Bosch, Nature, arXiv:1211.6429
NGC 1277, M~1.2 1011M☼, MBH~1.7 1010M☼
5. Nature: Simcoe et al., 2012,
QSR ULASJ120+064, z=7.08, Zmet< 10-4Z☼
SMBH formation
• Accretion of baryons from a thin/thick
or HMD disk, major or minor mergers,
from Pop III BH remnants (Shapiro 2005).
• Problems: small mass of remnants (<103M☼)
• For the observed SMBHs MBH~(105 – 1010)M☼
• The expected mass amplification is (103 – 104).
• Primordial BH (Ricotti et al. 2007, Duching
2008)
Three scenario of the BH formation
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Simplest problem – first galaxies and POP III stars
Two processes of the H2 formation
H+e=H-+γ, H-+H=H2+e, γ~1.6eV
H+p=H2+ +γ, H2++H=H2+p
Epar=128K, Eort=512K
In both case the reaction rate and the H2
concentrations are proportional to <ne>=<np>
At 1000>z>zrei xe=ne/<n>~10-3 what is very small value.
Feedback of LW radiation 912A<λ<1216A
H2+γLW =2H
Redshift variations of intensity of the UV
background
SMGs, Yun et al., 1109.6286
Gonzalez V., 2011, ApJ, 735, L34
Observed galaxies and IGM
Ωmet as the cumulative measure
z~10 Ωreio >(1 – 8)10-8
• z~0, Ωmet~5.7 10-4
• z~2.5 Ωmet~3. 10-5 for
galaxies with Mstar>109Mo
Ωstar~4 10-6,
• Ωmet~10-2Ωstar~4 10-8
• Possible explanations :
• a. Low massive galaxies ?,
b. non thermal sources
c. strong non homogeneity
• z~7,
(bubbles)
UV luminosity density
Oesch P., 2012, ApJ.745, 110
MJ , Bromm et al., 1102.4638
XXXXXX OBSERVATIONS
• 5-year WMAP data:
• τe=0.087±0.017,
zrec=10.8±1.4
• However: Pol~ΔT2τe, and ΔT2(DV)=2ΔT2(WMAP)
• Therefore, τe<0.9 and zrec<10.8
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BUT
Quasars and galaxies are seen at z~8 - 9
τe~0.04 – 0.05,
z~7
τe~Δτe~0.001 – 0.06, 7< z <1000
One object at z~9.5,
Observed galaxies and IGM
Ωmet as the cumulative measure
We like to have at least
fesc~0.1 – 0.01, Nbp>1, Nph~5 105
Ωmin=ΩbNbp(fescNph)-1~10-7(Nbp/fesc)(Ωb/0.04)
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z~2.5, Ωmet~3 10-5
for galaxies,
z~2.5, Ωmet~2.3 10-6 for IGM,
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Zmet=0.1Z☼~2 10-3,
Ω*~6.7 10-5, Ωmet=Ω*Zmet~ 1.3 10-7 for galaxies
ΩC~(5±1.7) 10-8, z<5.5, ΩC~(4.5±2.6) 10-9, z>5.5,
z~5,