Formation of the 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 and ionizing bubbles Bubble model, UV-background, non homogeneities in x H and T g z~ 10 WMAP: τ T ~0.1, x H =n H /n b << 1 z~6.5 – 5 - high ionization, x H ~10 -3 z< 3 - x H ~ We do not see any manifestations of the first stars 2. We do not know the main sources of ionizing UV radiation

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Possible sources of ionizing UV background 1. exotic sources – antimatter, unstable particles, etc… 2. First stars Pop III with Z met <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)~3T z 10 3/2, T 4 ~2. For z 10 >1 recombination becomes important ! Thermal sources: E~7 MeV/baryon, N γ < /baryon Non thermal sources - AGNs and Black Hole E~ 50 MeV/baryon, N γ ~ /baryon Ω met ~ Ω bar ~ , Ω bh ~ Ω bar ~ f esc ~ , N bγ ~1 - 2

Labbe I., 2010,ApJ.,708,L26, Spitzer photometry Z~8, 63 candidats, 20 actually detected SMD for M<-18 ρ * (z=8)~10 6 M s /Mpc 3 Ω * (z=8)~ Ω met (z=8)~ Ω reio ~10 -7 – z~2.5, Ω met ~ for IGM, Ω met ~ for galaxies

Three steps of galaxy formation 1. Formation of the virialized relaxed massive DM cloud (perhaps, anisotropic) at z<z rec ~10 3 with ρ cl ~200 and overdensity δ DM ~10 4 z 10 7 M 9 1/2 2. Cooling and dissipative compression of the baryonic component, but the bulk motions and the kinetic temperature of stars are preserved 3. Formation of stars – luminous matter with M>M J Main Problem of the star formation M J /M ¤ ~2 ·10 7 T 4 3/2 n b -1/2, For stars: T 4 ~10 -2, n b >10 2 cm -3, M J /M ¤ <10 3 z=z rec,T 4 ~0.3, n b ~250 cm -3, M J / M ¤ ~ 2 ·10 5 Parameters of baryonic components ~4· z 10 3 g/cm 3, ~ g/cm 3, ~1 g/cm 3, ρ BH ~2 M 8 -2 g/cm3 Cooling factors: H 2 molecules and metals (dust, C I etc.)

Simplest problem – first galaxies and POP III stars Two processes of the H 2 formation H+e=H - +γ, H - +H=H 2 +e, γ~1.6eV H+p=H 2 + +γ, H 2 + +H=H 2 +p E par =128K, E ort =512K In both case the reaction rate and the H 2 concentrations are proportional to = At 1000>z>z rei x e =n e / ~10 -3 what is very small value. Feedback of LW radiation 912A<λ<1216A H 2 +γ LW =2H

Influence of the LW background Actual limit is J LW21 ~1 – 0.1 for various redshifts For the period of full ionization z~10 we get J LW 21 ~4 N bγ This means that at at 10>z>8.5 the H 2 molecules are practically destroyed and star formation is strongly suppressed This background is mainly disappeared at z~8.5

Safranek-Shrader, Corrections for both limits ~10 times J 21 ~4N b γ

Simulations (2001) The box ~1Mpc, cells, N dm ~10 7, m dm ~30M 0, M gal ~10 6 – 10 7 M 0 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 M~ M s T 4 ~0.3 n b ~10cm -3 f H2 ~ j 21 ~1 M J (25)~10 4 M s M J (20)~500M s Lazy evolution, Monolitic object Monotonic growth ρ(z)??? Instabilities!

Smith, B.,2008, MNRAS, 385, 1443

Cooling functions.

ρ, T & Z, Wise Formation of massive galaxies owing to the merging of low mass galaxies.

Comments Importance – instead of the experiment Complexity, representativity and precision (WMAP). Modern facilities Our attempts – simulations versus analysis

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 pressure and kinetic temperature c. what is the cooling of the baryonic components d. thermal instability leads to formation of stars with masses M st > M Jeans

Analytical characteristics for DM component For the NFW halo with mass M=10 9 M 9 M s formed at z f =(1+z)/10 Within central core with r< r s we have ρ DM ~ g/cm 3 M 9 1/2 z f 10, T DM ~40 eV M 9 5/6 z f 10/3 m DM /m b Cooling factors: H 2 and atomic for T 4 >1, Three regimes of the gas evolution – slack, rapid and isothermal Thermal instability and the core formation Stars are formed for T bar 100cm -3 with M star > M J ~ T 4 3/2 /n bar 1/2 M s

Formation of the first stars with M cl /M 0 = and , z f =24 (left) and M cl /M 0 = and , z f =11 (right)

Low mass limit for the rapid-lazy formation of the first galaies

SN explosions W=GM 2 /R vir ~3·10 55 z 10 M 9 5/3 erg E SN ~10 52 – erg D ex <0.2 – 0.5 Mpc - IGM impact For M 9 >0.1 we have SN metal enrichment within galaxy, otherwise – matter ejection Low massive stars, satellites and merging

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Ellis et al. arXiv

Bradley L., , 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?

Behroosi et al

Behroozi et al., SFR(M h ) SMF~M h -4/3, M>M ch ; SMF~M h 2/3, M<M ch (left panel) M s /M h <2 – 3% at all z! ?continual evolution?

comments 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.

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 DM parameters ρ~ 0.07M 6 1/2 f 3 (M 6 ) P~37f 4 (M 6 ) S~14M /f(M 6 ) Z 10 =0.9M 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 -4 Mpc -3 Very massive BHs are observed as QSRs with N qsr ~10 -5 – Mpc -3 at z<5; mainly at z~2 – 2.5 Perhaps, there are AGNs in 70% of old massive galaxies. ρ BH ~ M 9 -2 g/cm 3, ρ DM ~ z f 10 M g/cm 3 within halo

Vestergaard et al. 2008

BH-distributions: M(z) & L/L ed Vestergaard, Osmer, 2009, ApJ,699,800

Number density of the SMBH, Kelly et al., 2011,

BH evolution 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: NGC 1277, M~ M ☼, M BH ~ M ☼ 5. Nature: Simcoe et al., 2012, QSR ULASJ , z=7.08, Z met < Z ☼

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 (<10 3 M ☼ ) For the observed SMBHs M BH ~(10 5 – )M ☼ The expected mass amplification is (10 3 – 10 4 ). Primordial BH (Ricotti et al. 2007, Duching 2008)

Three scenario of the BH formation

The end

Redshift variations of intensity of the UV background

SMGs, Yun et al.,

Behroozi et al., Stellar mass vs. host halo Similarity of the curves

Gonzalez V., 2011, ApJ, 735, L34

Observed galaxies and IGM Ω met as the cumulative measure z~10 Ω reio >(1 – 8)10 -8 z~0, Ω met ~ z~2.5 Ω met ~ for galaxies with M star >10 9 M o z~7, Ω star ~ , Ω met ~10 -2 Ω star ~ Possible explanations : a. Low massive galaxies ?, b. non thermal sources c. strong non homogeneity (bubbles)

UV luminosity density Oesch P., 2012, ApJ.745, 110

M J, Bromm et al.,

XXXXXX OBSERVATIONS 5-year WMAP data: τ e =0.087±0.017, z rec =10.8±1.4 However: Pol~ΔT 2 τ e, and ΔT 2 (DV)=2ΔT 2 (WMAP) Therefore, τ e <0.9 and z rec <10.8 BUT Quasars and galaxies are seen at z~8 - 9 τ e ~0.04 – 0.05, z~7 τ e ~Δτ e ~0.001 – 0.06, 7< z <1000 One object at z~9.5,

Observed galaxies and IGM Ω met as the cumulative measure We like to have at least f esc ~0.1 – 0.01, N bp >1, N ph ~ Ω min =Ω b N bp (f esc N ph ) -1 ~10 -7 (N bp /f esc )(Ω b /0.04) z~2.5, Ω met ~ for galaxies, z~2.5, Ω met ~ for IGM, z~5, Z met =0.1Z ☼ ~ , Ω * ~ , Ω met =Ω * Z met ~ for galaxies Ω C ~(5±1.7) 10 -8, z 5.5,