Early stars and galaxies :reionization of the

Universe

A. Doroshkevich, M.Demianski

Astro Space Centre of Lebedev Physical Institute

University of Warsaw

Progress in cosmology• Measurements of H0 - SN, Hubble

• CMB - COBE & WMAP, ….

• Surveys of galaxies - SDSS & 2dF,

• High precision observations of the

Ly- α forest, metal systems, QSRs

and galaxies at z=5 – 7 - ?- 10,

• Simulations – LSS, halos …

Main result – standard cosmological model

• Eucledian space Ωtot = 1. ± 0.05

• Hubble h = 0.7 ± 0.04

• Dark energy ΩΛ = 0.7 ± 0.1

• Dark matter Ωm = 0.24 ± 0.02

• Baryonic matter Ωb = 0.044 ± 0.004

• Galaxies Ωgal ~ (0.06-0.3)Ωb

• Relict CMB Trad =2.726 K

Main problems

• 1. Nature of the Dark Energy at small

redshifts and in the inflation period. • 2. Nature and composition of the Dark Matter.

• 3. Reliability of the ‘standard’ model.

• 4. Test of the inflation models.

• 5. Evolution of the Universe at 3< z< 1000 :

first galaxies and reionisation of the Universe.

Theoretical expectations and observational problems

• z~25 – 30 - formation of the first stars• z~12 – 9 -start of the reionization,, xH=nH/nb~1

• Bubble model, non homogeneities in xH and Tg

• 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 have no models of the LAE formation • 3. We do not know the main sources of ionizing • UV radiation

Reliability of the standard modelSteven Weinberg ‘Dreams of a final theory’

• Экспериментатор знает теоретический результат до того, как он начинает эксперимент. Поэтому возникает естественное желание вносить поправки лишь до тех пор, пока не получится «правильное» значение, а затем перестать искать другие поправки.

Но экспериментаторы все же не всегда получают ожидаемые результаты, что свидетельствует о силе их характера.

Possible sources of ionizing UV background

1. unknown sources – antimatter, unstable particles etc…

2. First stars Pop III with Z<10-5 or

Pop II, SNs, GRBs.

7 MeV/baryon, Nph~5 105 /baryon

3. non thermal sources - AGNs and Black Holes

• E~50MeV/baryon, Nph~3.5 106 /baryon

4. Quasars at z < 3.5 - 3

Spectra of quasars at z>6 – Spectra of quasars at z>6 – evidences of reionization, xevidences of reionization, xHH~10~10-5 -5 - 10 - 10-3-3

Optical depth in Ly-α and Ly-β lines

tauα~exp(z-4.2)~FUV , tauT~0.09

xH~10-5 at z<4, xH ~10-3 at z~6, xH~1 at z>9

Reionization of the Universe at (9-12)> z >(6 – 7) is the complex prolonged process .

First stars with Z<Zcr~10-5

Teff~105K Tage~3Myr L~M e± instability

stability of star formation: rotation, feedback, …

Three types of observed galaxies

• Ly-α emitters: 3Myr<Tag<300Myr, M*~107-109M

• LBG : 0.3Gyr<Tag<1Gyr, M*~109 – 1010M

• Distant red galaxies: 1Gyr<Tag, M*>1010M

• For all types – Rgal~1kpc,

• high density of stars, similar to buldge of early type• Luminosity function• Φ=Φ*10-x(α+1)exp(-10-x),x=0.4(M-M*),M*=-20.7,α=-1.8• Methods – HST, Spitzer, KEK,

• Spectra for the Brazual – Charlot model

HST, Spitzer, IRAC: LAEs and LBGs at z=5

Galaxies at z=3.1 and z~6, method

Redshift evolution of the mean density of stars –

saturation at z~1.5, Ω*~10-2.4-0.35z

ρst~108.6-0.35z MMpc-3, ngal~(1-10) 10-4Mpc-3, nLBG(z=3)~4h310-3Mpc-3, ngal(z=0)~10-2h3Mpc-3

Metallicity from damped Ly-α systems

Fit Z/Z~0.2 10-0.25z

What can do observed galaxies - Ωmet as the cumulative measure

• We have at z~5:

• Ω*~6.7 10-5, Ωmet=Ω*Zmet~ 1.3 10-7

• We like to have at least

• fesc~0.1 – 0.01, Zmet=0.1Z~2 10-3,

• Nbp>1, Nph~5 105

• Ωmin=ΩbNbp(fescNph)-1~10-7(Nbp/fesc)(Ωb/0.04)

Real bubbles

• For observed older massive galaxies with

• M*~1011M, Ngal~1.4 10-5Mpc-3, Mi~fescZNphM*~20M*

• Bubble size Ri~5.5Mpc,

• Volume fraction fi=Mingal/ρb ~10-2

• Additional sources:

• AGNs and BH,

• Dwarf satellites

Songaila-01, ΩC(z)=(5.2±1.7) 10-8,19 QSRs, 367 lines BSR-03, ΩCz4

2=(8 ± 4)10-8, z4=(1+z)/4, 9 QSRs,908 lines

at z~5 - 6 IGM ΩC(z)=(2 - 4) 10-8, GAL ΩC~2.6 10-8,

Dwarf satellites – pollution of IGM

• Observed in IGM ΩC~(2 – 4)10-8 at z~5

• Observed in galaxies ΩC =0.2Ωmet ~3 10-8

• at z~5

• Bubble of metals with R~2h-1Mpc, M*~1012M

• Dsep~24z4-2h-1Mpc, z4=(1+z)/4

• It agrees with high efficiency of satellites.• But we do not see so many satellites

• near MW at z=0 ?phantoms?

AGNs and BHs• Accretion is 7 times more effective than 12H→C12

• BH are observed in ~1% of all galaxies, n~10-4Mpc-3

• Very massive BH are observed as QSRs with

• Nqsr~10-5Mpc-3 and it is maximal at z~2 – 2.5

• One AGN is directly observed at z=5.44• Perhaps, there are AGNs in 70% of old massive

galaxies.

Problems again • We do not see any manifestations of • the first stars• We do not know the main sources of ionizing • UV radiation • A. first stars Pop III or Pop II, SNs, GRBs • are not effective • B. non thermal sources AGNs and/or BHs• are more effective • C. unknown sources – antimatter, unstable

particles etc.

The endThe end

Expectations• z~25 – 30 - formation of the first stars

• z~12 – 9 -start of the reionization,, xH=nH/nb~1

• Bubble model, non homogeneities in xH and Tg

• z~6.5 – 5 - high ionization, xH~10-3

• z< 3 - xH~10-5

• Sources of ionizing UV background• 1. First stars with Z<10-5

• 2. AGNs and Black Holes (BH)

• 3. Quasars at z < 3.5 - 3

Problems• 1. We do not see any manifestations of

• the first stars• 2. Formation of LAEs

• 3. We do not know the main sources of ionizing

• UV radiation • A. first stars Pop III or Pop II, SNs, GRBs

• E~7 MeV/bar, Nph~5 105 /bar

• B. non thermal sources - AGNs and/or BHs

• E~50MeV/bar, Nph~3.5 106 /bar

• C. unknown sources – antimatter, unstable particles