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 Fan+06 Presence of SMBHs to power these quasars, M BH ~10 9 M ⊙ at z>6 Presence of large stellar component in host galaxies, M star > 10 11 M ⊙ Presence of copious molecular gas M gas ~10 10 M ⊙ and dust M dust ~10 8 M ⊙ in the quasar hosts

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. Multi-scale Cosmological Sims (GADGET2 Springel 05) + ART 2 (Li et al 08) (All-wavelength Radiative Transfer with Adaptive Refinement Tree) Formation, evolution & multi-band properties of galaxies & quasars CART Cosmological All-wavelength Radiative Transfer

6. Multi-scale simulations –cosmological simulation in 3 Gpc 3 –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 (10 4-5 M ⊙ ) Self-regulated BH growth model –Bondi accretion under Eddington limit –Feedback by BHs in thermal energy coupled to gas Formation of z~6 Quasars from Hierarchical Mergers

8. Age of Universe (Gyr) Redshift z ~ 10 3 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 M BH ~ 2*10 9 M ⊙, M * ~ 10 12 M ⊙  Magorrian relation Li et al 07 Co-evolution of SMBHs and Host

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

10. 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 L x (L ⊙ ) L FIR (L ⊙ ) L B (L ⊙ ) L FIR (L ⊙ )

11. SPH cosmological simulations with BHs They form in massive halos in overdense regions They are highly clustered May provide patchy ionization of HI Z>6 Galaxies & Quasars in a Cosmological Volume stars Y (h -1 Mpc) X (h -1 Mpc) BH Log Ifrac X (h -1 Mpc) quasar galaxy

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

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. Birth place: massive halos in overdense region –Clustering, cross correlations of galaxies and quasars –Lensing Triggering mechanism: hierarchical merger –Morphology, pairs, CO maps –M BH --  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 –M BH -- M host relation Predictions & Observational Tests