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The End of the Dark Age & The Formation of the Structure of the Universe

The End of the Dark Age & The Formation of the Structure of the Universe. Jaan Einasto & Enn Saar Tartu Observatory Tartu Workshop August 2005. Overview. A short history of the evolution of the Universe Ionization history of the Universe Observational evidence for early evolution

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The End of the Dark Age & The Formation of the Structure of the Universe

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  1. The End of the Dark Age& The Formation of the Structure of the Universe Jaan Einasto & Enn Saar Tartu Observatory Tartu Workshop August 2005

  2. Overview • A short history of the evolution of the Universe • Ionization history of the Universe • Observational evidence for early evolution • Modelling of evolution • The growth of massive DM halos • Formation & evolution of quasars in merging galaxies • Evolution of the density field • Conclusions

  3. A short history of the evolution of the Universe

  4. Detecting The Cosmic Reionization From High-z Quasar Spectroscopy Djorgovski 2003

  5. Reionization history Primordial Pop III massive stars and young quasars reionize the universe at z ~ 15 ± 5 Their feedback may disrupt their hosts and inhibit further massive star formation, until a normal IMF, Pop II stars start forming, leading to a second reionization at z ~ 6 (Cen 2002)

  6. Lya Forest at z < 5: the Universe is filled w. ionized bubbles of H. At z > 5 bubbles are rare & space is opaque for Lya emission (Djorgovski 2003) Fan et al. AJ 128, 515, 2004

  7. High-z QSOs Are Very Metal Rich! Solar Dietrich, et al. 2003, ApJ 589, 722

  8. QSOs are more metal-rich than the DLA galaxies at comparable redshifts … or even the Milky Way disk stars today! QSOs The only known stellar populations with comparable metallicities are the cores of massive elliptical galaxies. disk stars DLAs Lu et al.

  9. Abundance patterns of QSO-s are similar to those of elliptical galaxies: enhanced Fe/ Mg SNe II (massive stars) Fe SNe I (WDs) time delay of ~ 0.2 - 0.6 Gyr  Start the enrichment at z ~ 10 ! Dietrich et al. 2003

  10. The mass of the BH is correlated with the magnitude and velocity dispersion of parent galaxies (open symbols – spirals, filled –ellipticals) (Ferrarese 2004)

  11. Masses of bulges of galaxies/DM halos and central black holes are closely related (Ferrarese 2004 astro-ph/0411247)

  12. To understand the formation and evolution of populations of the Universe numerical analysis is needed The formation of Pop III stars - hydrodynamical simulations which include: neutral & ionized hydrogen & hydrogen molecules; neutral, singly & doubly-ionized helium etc. (Abel et al. 1998, ApJ 508, 518) Millennium simulation with 21603 = 1010 particles in a cube of size 500 Mpc/h Springel et al astro-ph/0504097 Nested sequence of N-body resimulations to improve spatial resolution, including molecular and atomic cooling (Gao, White et al. astro-ph/0503003) Galaxy merger simulation that includes radiative cooling, star formation, BH growth, feedback from SN and accretion onto BH (Di Matteo et al astro-ph/0502199)

  13. Formation of Pop III stars Pop III stars form in knots of filaments of early DM structures at high redshift. (Abel et al. 1998, ApJ 508, 518) At redshift z=50 the gas density & temperature in knots grow to levels favorable to create H molecules, H2 cooling time becomes shorter than H recombination time. At the center of a DM-knot (mini-galaxy) just one massive Pop III star forms. Radiation of this star and its SN reionize IGM preventing the formation of more Pop III stars.

  14. Following the evolution Millennium simulation has the highest spatial resolution DM density field at z=0 in a slab of thickness 15 Mpc/h

  15. Environment of a rich cluster at high & low redshift. Left: DM distribution Right: galaxies overlayed with DM; colours of galaxies correspond to their stellar B-V colour index. At z=6 galaxies are blue, at z-0 mostly red. At the center of the 1st ranked galaxy a quasar (BH) is located

  16. The growth of massive DM halos Using Millennium Simulation as background hydrodynamical simulations allow to investigate the growth of individual massive DM-halos – rich clusters of galaxies (Gao, White et al. astro-ph/0503003).

  17. The growth of mass M & temperature T of a massive halo in simulation. At redshift z= 40 T = 104; molecular hydrogen forms and starts cooling forming first pop III stars in nuclei of mini-galaxies. Radiation from pop III stars & supernova explosions heats the surrounding has and inhibits further star formation. Surrounding gas is enriched with heavy elements. (Gao, White et al. astro-ph/0503003)

  18. DM density fields at z=49 and z=0 centered on a high-density peak. The size of the box is 190 times larger than the radius of the central DM-halo. Filaments are seen at both epochs, luminous objects form in knots. (Gao, White et al. astro-ph/0503003)

  19. Formation & evolution of quasars in merging galaxies Evolution of 2 galaxies with and w/o Black Hole. The peak of star formation & BH accretion is reached at 1.6 Gyr. Strong wind from accretion to BH expels gas from inner region. Remnant with BH is spheroidal galaxy with little gas. (Di Matteo et al astro-ph/0502199)

  20. Star formation rate, BH accretion rate & growth during galaxy-galaxy merger for 3 models w. various virial velocity (mass). Dots identify panels in previous Figure. (Di Matteo et al astro-ph/0502199)

  21. The relation between final BH mass & velocity dispersion of stars of the bulge. Solid circles show results for 6 merger simulations, open circles show results of the same 6 mergers with different gas fraction. Black symbols show observational data. (Di Matteo et al astro-ph/0502199) Mergers lead to strong inflow that generates a burst of star formation and feeds gas to the supermassive BH

  22. Evolution of the density field Size 200 Mpc/h 2563 particles z=5 z=2 z=1 z=0 The contraction of superclusters, the merging of filaments in superclusters and expansion of voids (low-density regions) is seen JE (in prep.)

  23. Conclusions • The reionization (Dark Age) can be divides into 3 epochs: 1) cold DA, baryon gas neutral & opaque to Lya z > 15 2) hot DA, baryon gas partly ionized, opaque to Lya, 6 < z < 15 3) Bright Age, baryons ionized, transparent to Lya, z < 6 • The Universe was reionized twice, by Pop III stars & SN at z~15 and by Pop II stars & SN at z~6 • The formation of first Pop III stars in dense knots of DM (protogalaxies) starts at z~50 • Pop III stars enrich the IGM, so that Pop II stars contain metals. Evolution & chemical enrichment in cores of galaxies is very rapid • Early galaxies merge giving rise to rapid growth of supermassive BH-s in central regions; the accreting gas powers BH-s to quasars • Further evolution of the structure is both by infall of DM and gas and by merging of galaxies

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