Quasars at the Cosmic Dawn

1. Quasars at the Cosmic Dawn Yuexing Li Penn State University Main Collaborators: Lars Hernquist (Harvard) Volker Springel (Heidelberg) Tiziana DiMatteo (CMU), Liang Gao (NAOC)

2. The Most Distant Quasars Discovered Presence of SMBHs to power these quasars, MBH~109 M⊙ at z>6 Presence of large stellar component in host galaxies, Mstar > 1011 M⊙ Presence of copious molecular gas Mgas~1010 M⊙ and dust Mdust~108 M⊙ in the quasar hosts Fan+06

3. 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: some 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)

4. 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

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

6. Formation of z~6 Quasars from Hierarchical Mergers • Multi-scale simulations • cosmological simulation in 3 Gpc3 • Identify dark matter 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 • Each galaxy progenitor contains a 100 M⊙ BH seed • Left behind by PopIII stars • Grows at Eddington rate until it enters merger tree (104-5 M⊙) • Self-regulated BH growth model • Bondi accretion under Eddington limit • Feedback by BHs in thermal energy coupled to gas

8. 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

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

10. LFIR (L⊙) LFIR (L⊙) Lx (L⊙) LB (L⊙) 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

11. stars BH galaxy Y (h-1 Mpc) Log Ifrac quasar X (h-1 Mpc) X (h-1 Mpc) Z>6 Galaxies & Quasars in a 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

12. Predictions for Future Surveys JWST

13. Can z>6 SMBHs form from ~100 M⊙ BH seeds? • BHs from PopIII stars at z~20-30 may have ~100 M⊙ • This would require BHs accrete at near Eddington rate for much of its early life • Previous studies suggest that radiative feedback strongly suppresses BH accretion rate • Johnson & Bromm 07, Alvarez+08: AR <1% Eddington • Milosavljevic+08,09: AR ~30% Eddington • However, we should note that • Not every BH seed grows into a SMBH • Small box in simulations may prevent gas replenish • Self-gravity may boost accretion

14. Accretion onto ~100 M⊙ BH Seeds • 1-D spherical accretion, including gas self-gravity • Modified VH1 code (Blondin & Lufkin 93) • Logarithmic grid, 10-4 -1 pc • Feedback processes • Photoionization heating • Radiation pressure • Thomson scattering • photoionization

15. Self-gravity Aided Accretion

16. Self-gravity Aided Accretion

17. Summary • The first SMBHs can form from ~100 M⊙BH seeds in high overdensity peak with abundant gas supply, because self-gravity overcomes radiative feedback and boots accretion rate • Luminous z~6 quasars can form in the LCDM cosmology via hierarchical mergers of gas-rich proto-galaxies • 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

18. 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