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Galaxies and Quasars in the Epoch of Reionization

Galaxies and Quasars in the Epoch of Reionization. Yuexing Li Keck Fellow Harvard-CfA. Main Collaborators. Thoeretical: Lars Hernquist (CfA), Volker Springel (MPA), Tiziana Di Matteo (CMU), Tom Abel (Stanford)

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Galaxies and Quasars in the Epoch of Reionization

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  1. Galaxies and Quasars in the Epoch of Reionization Yuexing Li Keck Fellow Harvard-CfA

  2. Main Collaborators • Thoeretical: Lars Hernquist (CfA), Volker Springel (MPA), Tiziana Di Matteo (CMU), Tom Abel (Stanford) • Observational:Giovanni Fazio (CfA), Xiaohui Fan (Arizona)

  3. Cosmic Hisotry • recombination • Cosmic Dark Ages: no light no star, no quasar; IGM: HI • First light: the first galaxies and quasars in the universe • Epoch of reionization: radiation from the first objects lit up and ionize IGM : HI  HII  reionization completed, the universe is transparent and the dark ages ended today Courtesy: George Djorgovski

  4. HST Chandra Spitzer SDSS Subaru SWIFT GLAST MAMBO …. Courtesy: Edo Berger Exciting Era for High-z Objects Fan+01,03,04,06 Schneider+03,05,07 Willott+07 …. Giavalisco+04 Bouwens+06, 07 Thompson+05, 06 Iye+06, Yan+06 …. Brandt+02 Shemmer+06 Bertoldi+03, Carilli+04 Beelen+06, Jiang+06 Maiolino+04, Wang+07 … Schady+08 Fynbo+08 … Presence of large stellar component in galaxies, Mstar > 1011 M⊙ at z>6 Presence of SMBH in quasars, MBH~109 M⊙ Presence of copious dust Mdust~108 M⊙ in these objects

  5. Questions & Myths I: Can such massive objects form so early in the LCDM cosmology? • myth: there is a “cut-off” at z~5 (Efstathiou & Rees 88) • myth: exotic mechanisms required, e.g., super-Eddington accretion (Volonteri & Rees 05, 06); supermassive BH seeds (Bromm & Loeb 03, Haiman 04, Dijstra+08) II: How do they grow and evolve? • myth: z~6 quasars have “undersized” host galaxies (Walter+2003) • myth: SMBH – host correlations don’t hold at high z III: What are their contributions to IR emission and reionization? • myth: all FIR comes from star heating (Bertoldi+2003, Carilli+2004) • myth: quasars don’t contribute to reionization (e.g., Gnedin+04)

  6. Modeling Galaxies & QSOs • Physics to account for close link between galaxy formation and BH growth • SMBH - host correlations (e.g, Magorrian+98, Gebhardt+00, Ferrarese+00, Tremaine+02…) • Similarity between cosmic SFH & quasar evolution (e.g., Madau+95, Shaver+96) • Hydrodynamic simulations to follow evolution of quasar activity and host galaxy • Large-scale structure formation • Galactic-scale gasdynamics, SF, BH growth • Feedback from both stars and BHs • Radiative transfer calculations to track interaction between photons and ISM /IGM • Radiation from stars & BHs • Scattering, extinction of ISM & reemission by dust • Evolution of SEDs, colors, luminosities, AGN contamination

  7. CARTCosmologicalAll-wavelength Radiative Transfer GADGET2(Springel 05)+ART2 (Li et al 08A)(All-wavelength Radiative Transfer with Adaptive Refinement Tree) Formation, evolution & multi-band properties of galaxies & quasars

  8. Zoom-in sims Zoom: HR-region ~60 h-1Mpc, 4003 Y (h-1 Mpc) X (h-1 Mpc) I: Quasar Formation - MIM • Multi-scale simulations with GADGET2 (Springel 05) • N-body cosmological simulation in 3 Gpc3 • Identify halos of interest at z=0 • Zoom in & re-simulate the halo region with higher res. • Merging history extracted • Re-simulate the merger tree hydrodynamically • Self-regulated BH growth model (DiMatteo et al. 05) • Bondi accretion under Eddington limit • Feedback by BHs in thermal energy coupled to gas

  9. G1 G2 G3 G4 G5 G6 G7 G8 7.7x1012 M⊙ Formation of a z~6 QSO from Hierarchical Mergers • Merger tree with 7 major mergers z~14-7 • Idealized galaxy using MMW model with properties (Mvir, Rvir, Cvir) scaled with z (Mo+98) • BH seeds from remnants of PopIII stars (Abel+02, Bromm & Larson04, Yoshida+06, 08), M=200 M⊙ at z=30 • BH binary merge when separation below resolution: • At high-z, the potential well is deeper because galaxies are more compact • BH binary merge rapidly in gaseous environment (Escala+04,05) • Gravitational recoil may eject BH if Vkick > Vesc, Vkick ~100 – 475 km/s (e.g., Gonzalez+07, Campanelli+07) • Maximum Vkick < 200 km/s in gas-rich galaxy mergers (Bogdanovic+07) • Our halos have Vesc > 300 km/s

  10. Age of Universe (Gyr) Co-evolution of SMBHs and Host • <SFR> ~ 103 M⊙/yr, at z>8, drops to ~100 M⊙/yr at z~6.5  heavy metal enrichment at z>10 • Indiv. BH grows via gas accretion, total system grows collectively • System evolves from starburst  quasar • Merger remnant MBH ~ 2*109 M⊙ , M* ~ 1012 M⊙  Magorrian relation Redshift z Li et al 07

  11. Opacity  (cm2/g) Y (kpc) rest (m) X (kpc) II: Multi-band Properties - ART2 • 3-D Monte Carlo RT code ART2 treats radiative equilibrium  calculate dust emission self-consistently (Bjorkman & Wood 01) • Adaptive grid (Jonsson06)  cover large dynamical range, capture inhomogeneous density distribution • Multi-phase ISM model (McKee & Ostriker 77) + GMC scaling relations (Larson 1981) • Supernova-origin dust model  dust in young, high-z objects (e.g., Maiolino+04, Todini & Ferrara 01)

  12. quasar-like starburst-like post-QSO Li et al 08A obs (m) Evolution of SEDs

  13. Li et al 08 LIR (Lsun) LFIR (L⊙) SFR LFIR (L⊙) F25um/F60um Lx (L⊙) Li et al 08B, in prep Li et al 08 LFIR LB (L⊙) Redshift z Origin of Thermal Emission • Quasar system evolves from cold --> warm • In peak quasar phase, radiation /heating is dominated by AGN • Starbusts and quasars have different IR-optical-Xray correlations

  14. stars BH galaxy Y (h-1 Mpc) Log Ifrac quasar Li et al. 08C, in prep X (h-1 Mpc) X (h-1 Mpc) III. Galaxies & Quasars in Cosmological Volume • SPH cosmological simulations with BHs • They form in massive halos in overdense regions • They are highly clustered • May provide patchy ionization of HI • SMBH -- host correlations hold Li et al 09, in prep

  15. Summary • CART is a powerful approach to study the formation, evolution, and multi-band properties of galaxies and quasars. • Luminous z~6 quasars can form in the LCDM cosmology  hierarchical mergers of gas-rich proto-galaxies, with BH accretion under Eddington limit. • Galaxy progenitors of these quasars are strong starbursts, providing important contribution to metal enrichment & dust production. • Early galaxies and quasars form in highly overdense region, highly clustered  patchy reionization

  16. Predictions & Observational Tests • Birth place: massive halos in overdense region • Clustering, cross correlations of galaxies and quasars • Lensing • Triggering mechanism: hierarchical merger • Morphology, pairs, CO maps • MBH --  relation • Merger rate • Evolutionary path: Starburst --> quasar • Star formation history, evolved stellar components, mass functions • Metal enrichment, molecular gas, dust • Thermal emission: stars --> AGN • SFR indicators • IR - optical relations • End product: SMBH -- host correlations • MBH -- Mhost relation

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