The Formation of S uper m assive B lack H oles in the Early Universe

1. The Formation of Supermassive Black Holes in the Early Universe Jian Hu Tsinghua Center for Astrophysics Sep 26, 2006

2. Outline • Introduction • SMBHs formation problem in the early universe • Some possible resolutions and their defects • Two phase accretion with dark matter and baryon • Summary and conclusions The 7th Sino-German Workshop

3. A brief cosmic history • recombination • Cosmic Dark Ages: no light no star, no quasar; IGM: HI We study here • First light: the first stars and quasars in the universe • Epoch of reionization: radiation from the first object lit up and ionize IGM : HI  HII  reionization completed, the universe is transparent and the dark ages ended  today The 7th Sino-German Workshop G. Djorgovski

4. Observational Facts • SMBHs are ubiquitous at the center of galaxies. • SMBHs has strong feedback effect on their host: formation of bulge (M4) and star formation. • High redshift (z>6) quasars contain SMBHs with mass greater than 109 M⊙ was found. The 7th Sino-German Workshop

5. High redshift quasars found by SDSS Fan et al. 2001 The 7th Sino-German Workshop

6. Most distant observedquasarSDSS 1148+5251 Found in 2001 by SDSS z=6.42 (age <0.9 Gyr)(Fan et al. 2001) MSMBH~ 3109 Msun (Willott et al 2003, Barth et al 2003) How to build a Supermasive Black Hole in the early universe？ The 7th Sino-German Workshop

7. Seed black holes: Pop III remnants • Simulations suggest that the first stars are massive M~100-600 Msun(Abel et al., Bromm et al.) • Metal free dying stars with M>260 Msun leaveremnant BHswith Mseed BH≥100 Msun (Fryer, Woosley & Heger) The 7th Sino-German Workshop

8. BUT, SMBH Growth was limited in the early universe! SMBH growth by Baryonic Eddington Accretion The growth of SMBHs via gas accretion is given by Where is the Salpeter timescale. Observations suggest:ε~ 0.1-0.2(Yu & Tremaine 2002); L/LEdd  1(Mclure & Dunlop 2004). Radiation efficiency required to build an SMBH with MSMBH=3*109 Msunvs. the formation epoch redshift of the seed black hole with Mseed=100-600 Msun. fduty~1 or effective merge is necessary, but… The 7th Sino-German Workshop

9. Possible solution IEffective BH merges (e.g., Yoo & Miralda-Escude 2004). But, binary center of mass recoil during coalescence due to asymmetric emission of GW(e.g. Fitchett 1983, Favata et al 2004, Blanchet et al 2005, Baker et al 2006) «vesc from today galaxies ≈vesc from high-z ones at z >10 more than 80% of merging MBHs can be kicked out of their halo(Volonteri & Rees 2006) ELLIPTICAL GALAXIES 1000 100 Vrecoil (km/s) Vesc (km/s) 10 DWARF GALAXIES/ MINIHALOS mass The 7th Sino-German Workshop 1013 109 By Rees

10. Possible solution IISuper-Eddington baryonic accretion But, super-eddington gas accretion will be rapidly halted by the strongfeedback of Compton heating and outflow(Wang et al 2006). • Radiative feedback will cause accretion rate oscillation, most time in non-accretion state (fduty~0.006). (Ciotti & Ostriker 2001) Ciotti & Ostriker 2001 The 7th Sino-German Workshop

11. Possible solution III IMBH seeds (~103-106 Msun) • Possibility: • Viscous angular momentum transport + efficient gas confinement: • supermassive stars => IMBHs (e.g. Haehnelt & Rees 1993, Eisenstein & Loeb 1995, Bromm & Loeb 2003, Koushiappas et al. 2004) • Bar-unstable self-gravitating gas + large “quasistar” (Begelman, Volonteri & Rees 2006) • Transport angular momentum on the dynamical timescale • Formation of a BH in the core of a low entropy quasistar ~104-106 Msun • The BH can swallow the quasistar • Need more numerical simulation / observational evidence. The 7th Sino-German Workshop

12. Our solution: two-phaseaccretionmodel(Hu et al., 2006, MNRAS, 365, 345) • Seed BH~100 M⊙, Pop III star remnant at z=~20-30. • Phase I: accretion of SIDM (Self-Interacting Dark Matter) • 100 M⊙→ 106M⊙ • Phase II: baryonic Eddington accretion • 106 M⊙→ 109M⊙ The 7th Sino-German Workshop

13. Phase I: accretion of SIDM Self-interacting dark matter (SIDM) is suggested to account for the profile of DM halo and overabundant dwarf halos problem (Spergel & Steinhardt 2000). Inner region of self-interacting dark matter halo can be treated as a fluid, so Bondi accretion occur (Ostriker 2000). Assuming a singular isothermal sphere (SIS) profile for the dark matter halo:(other profile, e.g. NFW, is also acceptable, cf. Hennawi & Ostriker 2002) This rapid accretion of SIDM ceases when the mean free path is greater than the accretion radius, which gives the accretion duration t1. After t1, a gradual transition will occur to a slower, diffusively limited growth of SIDM. The accretion rate is determined by the rate at which particles are scattered into the loss cone. The 7th Sino-German Workshop

14. Phase II: Baryonic Eddington accretion • When the rapid accretion of SIDM ceases, the accretion of dark matter turns into a much less efficient loss cone accretion and becomes unimportant compared with baryonic accretion at the Eddington-limit. • Several e-folding times are sufficient to raise the SMBH mass to ~109 M⊙. • Most of the BH mass is assembled during the second phase, consistent with arguments that SMBHs gain most of their mass via QSO accretion (e.g., Yu & Tremaine 2002). • Co-evolution of bulge and BH build the M- relations. The 7th Sino-German Workshop

15. SMBH accretion rate Baryonic Eddington SIDM Bondi ~108 yr time delay of the onset of efficient accretion (Johnson & Bromm 2006) SIDM diffusive Phase I Phase II The 7th Sino-German Workshop

16. SMBH growth history Phase I ~108 yr time delay of the onset of efficient accretion (Johnson & Bromm 2006) Phase II The 7th Sino-German Workshop

17. The beginning epoch of Phase I required by the early quasars J114816.64+525150.3 (z = 6.43, MBH =3  109M ⊙)J103027.10+052455.0 (z = 6.28, MBH =3.6  109M ⊙)J130608.26+035626.3 (z = 5.99, MBH =2.4  109M ⊙) The 7th Sino-German Workshop

18. Observational signature • If the IMBHs grow only by Phase I SIDM accretion, and the baryon accretion has never occurred for some physical reasons, e.g. the gravitational potential well of the halo is not deep enough to bind the baryons, we may find some dark mater halos (dark galaxies) with massive black holes at their centers but without the formation of galaxies – DM halo-IMBH system. • How to find such system? • Gravitational lensing? • Gas dynamics (HI 21cm survey)? The 7th Sino-German Workshop

19. Z>6 z=20~30 accretion SMBH merge Seed BH Summary: The roadmap of the first SMBHs formation Pop III remnants (100-600 Msun) or IMBHs (103-106 Msun) Eddington Or Super-Eddington (baryonic or DM) Effective or Ineffective Active or Inactive The 7th Sino-German Workshop

20. Conclusions • Two stage SIDM-baryon accretion can fully account for the SMBH formation in the early universe. • Our model predict existence of DM halo-MBH system. • Theoretical, numerical and observational works are required to constrain the picture of the first SMBHs formation. The 7th Sino-German Workshop