Post on 09-Jul-2020
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