Evidence for Feedback: Cosmological Reionization and High-z SMBH Growth Columbia University Reionization Workshop Beijing, China July 9-11, 2008 Zoltán Haiman

Outline of Talk Reionization History – observational clues from quasars & CMB – no-feedback model over-produces  e from WMAP3 – processes that can suppress earliest galaxies Growth of Supermassive BHs – contribution of accreting BHs to reionization and feedback – assembly of billion-solar mass SMBHs by z=6

Metal Enrichment: intergalactic gas enriched by heavy elements out to z~6 (ubiquitous but cold) Reionization: intergalactic gas highly ionized at z~6 (and possibly already at z~13) Stars and Black Holes at z>6 Massive Black Holes: >10 9 M  holes known to exist already at z~6 (their seeds must be in place at z>10) chemical/thermal/ionization state of IGM and star/BH formation are governed by global feedback processes ? ( no analog at low redshift )

Distant Quasars: Reionization at z~6?  x H   2   x H    x H  ≳ Fan et al z=5.82 z=5.99 z=6.28 Gunn-Peterson trough: Observational Breakthrough in 2002: SDSS quasars at z~6

Spectrum of a Pre-Reionization Source HIIHI ∢ Z=0Z=6 Z=7IGM Observed Wavelength (Å) Opacity (log  ) HII region (x HI ~ r 2 ) Two contributions to Ly  absorption: HII region (x HI ~ r 2 ) Gunn-Peterson wing

The Hunt for the GP Damping Wing redshifted wavelength (Å) optical depth - Create mock spectra: 300 lines of sight in a 300 lines of sight in a hydro simulation box hydro simulation box from Renyue Cen - Match observed statistic: (1) rapid loss of flux (1) rapid loss of flux Mesinger & Haiman (2004) (2) pixel opt.depth PDF (2) pixel opt.depth PDF Mesinger & Haiman (2007) - Fit 3 free parameters: R s (HII region size) R s (HII region size) x HI (neutral fraction) x HI (neutral fraction) L ion (ionizing luminosity) L ion (ionizing luminosity)

Pixel Optical Depth for z=6.28 quasar (Becker et al. 2001; White et al. 2003; 2004) observed wavelength (Å) flux (arbitrary units) modeling modeling (1)Fit for intrinsic emission from red emission from red side of Lya line side of Lya line (double Gaussian + NV) (2) Derive opt. depth in each pixel on in each pixel on blue side of line blue side of line (~30 pixels available)

Pixel Optical Depth PDF Results (z=6.22) (Mesinger & Haiman 2007) Inferred optical depth (   ) Fraction of pixels RsRs  HI  f ion Prob

Detection of a Cosmic Strömgren Sphere - R S = 6  0.3 Mpc (~40 comoving Mpc) - X HI ≳ L ion = ( )×10 57 s -1 - IGM significantly neutral Follows independently from (1) spectrum and (2) size of HII region - Ly  and Ly  can yield dynamic range to find ionization topology find ionization topology - constrain spectral hardness  E ion  < 0.2 keV  E ion  < 0.2 keV Implications: Results: (“2  ”) (“2  ”) - 4 quasars with full GP troughs show diversity Other quasars:

Quasars vs. GRB afterglows Conventional Wisdom: GRBs are better probes because 1. bright and seen to high-z 2. No HII region present 3. power-law spectrum  easier interpretation But… quasar spectra ultimately better probes 1. Statistical sample (>100 spectra) will be needed (GRBs appear to be too rare) 2. Large QSO HII region moves I-front to mean IGM (GRBs have intrinsic HI absorption) 3. Lyman  line modeling is not a limitation

Intrinsic Ly  Line Shapes Can we predict flux on blue side of Ly , using red side? Repeat fitting procedure using low-redshift templates - 46 HST spectra of 42 z<1 quasars - select spectra showing no absorption - use observed spectrum + model IGM to create mock z=6 spectrum - 6-parameter fit of 3 Gaussians (fix central wavelength) to red side - find best-fit x HI, R HI, L ion from blue side Scatter and bias in the inferred mean x HI in the IGM? Kramer & Haiman (2008, in preparation)

Recovered Fit Parameters Kramer & Haiman (2008, in preparation)

Recovered Neutral Fractions Kramer & Haiman (2008, in preparation)

Recovered Neutral Fractions (x HI =0.04) Kramer & Haiman (2008, in preparation)

CMB: Electron Scattering Optical Depth WMAP5 Polarization Anisotropy Dunkley et al. (2008) c.f.  =0.04 for z r = 6 1. early reionization or or 2. “tail” of partial Ionization to higher z

Primordial Gas Cooling log( Temperature / K ) log( cooling rate / erg s -1 cm 3 ) COSMIC TIME MASS SCALE Gas Phase Chemistry: H + e -  H - +  H - + H  H 2 + e - Virial Temperature Minihalo: T vir < 10 4 K

What forms in the early minihalos STARS: FIRST GENERATION METAL FREE - massive stars with harder spectra - boost in ionizing photon rate by a factor of ~ 20 - return to “normal” stellar pops at Z ≳ Z ⊙ (Tumlinson & Shull 2001 ; Bromm, Kudritzki & Loeb 2001; Schaerer 2002) SEED BLACK HOLES: (~ M ⊙ ) - boost by ~10 in number of ionizing photons/baryon - harder spectra up to hard X-rays: “pre-ionization” (Ricotti & Ostriker; Oh; Venkatesan & Shull; Madau et al.) - must eventually evolve to quasars and remnant holes - accreting BHs would overproduce unresolved soft XRB at 1 keV if they dominated reionization at z~6 (Dijkstra, Haiman & Loeb 2005)

Vanilla Reionization History (no minihalos) Wyithe & Loeb; Ciardi et al. Somerville et al.; Sokasian et al. Fukugita & Kawasaki; Cen; …. Haiman & Bryan (2006) N  = 4000 f * = 15% f esc = 20% C = 10  /C = N  f * f esc /C = 12  0.09 redshift ionized volume fraction Fixed by requirement that z(percolation) ~ 6 T min = 10 4 K

Expectations for Minihalos Ionizing sources: f * = (vs 0.15) - f * = (vs 0.15) N  = 80,000 (vs 4,000) - N  = 80,000 (vs 4,000) f esc = 1 (vs 0.2) - f esc = 1 (vs 0.2) Clumping evolution Excluded from from ionized regions cannot complete reionization at z~6 - cannot complete reionization at z~6 Simulations (e.g. Iliev et al. 2006)   N  f * f esc = 200 vs 120 C(z~15)=3 vs C(z=6)=10 in absence of feedback, minihalos could contribute to reionization:

Reionization History with Minihalos redshift ionized volume fraction efficiency Optical depth  0.19  0.09 Haiman & Bryan (2006) Minihalo contribution suppressed by a factor of ~10 (2  )

Feedback Processes INTERNAL TO SOURCES - UV flux unbinds gas - supernova expels gas, sweeps up shells - H 2 chemistry (positive and negative) - metals enhance cooling GLOBAL (FAR REACHING OR LONG LASTING) - H 2 chemistry (LW: negative X-rays: positive) - photo-evaporation (minihalos with  < 10 km/s) - photo-heating (halos with 10 km/s <  < 50 km/s) - entropy floor (inactive fossil HII regions or X-rays) - global dispersion of metals (pop III  pop II) - mechanical (SN blast waves) Do most minihalos fail to form stars or black holes?

SF/Reionization History Self-Regulates? Case 1 : No net feedback reionization completed early reionization completed early small halos small halos closely spaced closely spaced smooth smooth He/H close in time He/H close in time Case 2 : Negative feedback reionization completed later reionization completed later larger halos, larger halos, farther spaced farther spaced more patchy more patchy He/H farther in time He/H farther in time *IF* feedback regulates reionization history, then there will be a period with a robust ‘steady state’ solution for the star formation history - need to know J crit (M halo,z) log [d  * /dt/M  yr -1 Mpc -3 ] log [d  * /dt / M  yr -1 Mpc -3 ] redshift Haiman, Abel & Rees (2000)

Outline of Talk Reionization History – observational clues from quasars & CMB – no-feedback model over-produces  e from WMAP3 – processes that can suppress earliest galaxies Growth of Supermassive BHs – contribution of accreting BHs to reionization and feedback – assembly of billion-solar mass SMBHs by z=6

Growth of High-z Supermassive BHs z=6.43 z=20 CDM merger tree 1. Can growing BHs contribute significantly to reionization? 2. How are the z~6 SMBHs with M bh = few × 10 9 M  assembled?  min ~ 10 km/s M bh = few × 10 9 M 

Is Super-Eddington Growth Required? Example: SDSS (Fan et al. 2003) z=6.43 M bh  4 x 10 9 M  e-folding (Edd) time: 4 x (  /0.1) 10 7 yrΩ Age of universe (z=6.43) 8 x 10 8 yr  How did this SMBH grow so massive? (Haiman & Loeb 2001) No. e-foldings needed ln(M bh /M seed ) ~ 20 M seed ~100 M  Strong beaming? No. (Haiman & Cen 2002) Gravitational lensing? No. (Keeton, Kuhlen & Haiman 2004)

Gravitational radiation produces sudden recoil — kick velocity depends on mass ratio and on spin vectors — typical v(kick) ~ few  100 km/s (Baker et al. 2006, 2007 — maximum v(kick) ~ 4,000 km/s Gonzalez et al. 2007) Most important at high redshift when halos are small — escape velocities from z>6 halos is few km/s Major obstacle: gravitational recoil

Modeling Procedure Construct Monte-Carlo DM halo merger tree from z=6 to z> M ⊙ ≤ M halo ≤ M ⊙ (M res =few 10 5 M ⊙ ; N~10 5 trees) - seed fraction f occ of new halos with BHs (M seed =100 M ⊙ ) Gravitational Recoil - at merger, draw random v kick (Baker et al. 2008) - spin orientation: random or aligned - follow kicked BH trajectory -- damped oscillation (gas drag) - profile either  ∝ r -2.2 (cool gas) or flat core BH growth by accretion - merger delayed by dynamical friction time - seed initially in empty halo - duty cycle for accretion between maximum of Bondi and Eddington rate Tanaka & Haiman (2008, in preparation)

Trajectory of kicked BH Tanaka & Haiman (2008, in preparation) DM halo NFW DM halo NFW gas with gas with flat core flat core (Shapiro et al) (Shapiro et al) gas with gas with steep cusp steep cusp (Abel & Bryan) (Abel & Bryan)

SMBH mass function at z=6 Tanaka & Haiman (2008, in preparation)

Total mass in >10 5 M ◉ SMBHs: overproduced by a factor of ! Tanaka & Haiman (2008, in preparation)

Results from SMBH assembly (i) spin alignment (ii) f occ ≳ optimistic assumptions required (iii) f duty ≳ 0.8 The 10 9 M  BHs result from runaway early seeds (z>25) that avoided ejection at merger: asymmetric mass ratio Making few  10 9 M  BHs by z=6 without overproducing few  10 5 M  BHs (  BH ≦ 4  10 4 M  Mpc -3 ) suggests f occ ≈ and negative feedback at z~20-30 Growing BHs: X-ray pre-ionization (10-20%) and heating Alternative : a rapid (super-Eddington) growth phase }

Conclusions 1. WMAP+SDSS quasars together constrain early reionization: mini-halo contribution at z ≳ 15 suppressed by factor of ~10 2. Suppression can be caused by H 2 photo-dissociation by early LW background, or by X-ray pre-heating by BHs 3. GR kick major obstacle for early BH growth: few x 10 9 M  by z=6 requires uninterrupted Eddington accretion 4. Difficult to build 10 9 M  BHs without overproducing M  BHs: independent evidence for negative feedback at z~20

Remnants of Massive Stars Heger et al (for single, non-rotating stars) 10M  25M  40M  140M  260M  Z=Z Z=Z  Z=0 metalicity

SMBHs in T vir >10 4 K halos? SMBHs in T vir >10 4 K halos? Highly super-Eddington growth may be possible if gas remains at 10,000 Kelvin due to lack of H 2 and cools via atomic H lines Jeans mass M J  T 2 /  1/2 ≈ M ⊙ Behavior of gas has not been studied in nearly same detail as for minihalos (no 3D simulations) But we have a speculation, based on a MMW disk toy model (Oh & Haiman 2002)

Conclusion: T vir >10 4 K halos cool to ~100K Similar to minihalos: Rely on H 2 cooling and fragment on similar (few 100 M  ) scales Main difference: Main difference: contract to high densities less susceptible to feedback cf: HD reduces temperature and fragmentation scale? Uehara & Inutsuka 2000 Machida et al Johnson & Bromm 2005 cf: SMBHs Volonteri &Rees 2005 Bromm & Loeb 2005 Begelman et al Spaans & Silk 2006 (Oh & Haiman 2002)

Direct SMBH formation? Omukai, Schneider & Haiman (2008) Evolution of irradiated, metal-free gas: J 21 (crit) ≈ 10 3

Direct SMBH formation: impact of metals Omukai, Schneider & Haiman (2008) Including the effect of (1) irradiation and (2) metals

Dense star cluster, rather than SMBH? Omukai, Schneider & Haiman (2008) Two stringent conditions needed to avoid fragmentation: (i) J(LW) ≳ few 10 3  erg s cm -2 Hz -1 sr -1 (ii) Z ≲ 5  Z ☉ (ii) Z ≲ 5  Z ☉ First condition may be satisfied in rare (~10 -7 ) cases of a very close, bright & synchronized neighbor (Dijkstra, Haiman, Wyithe & Mesinger, in preparation) Second condition eased by factor of 100 if no dust (CII and OI cooling). Most likely case with floor metals will form a dense stellar cluster  collapse to IMBH of M 

Combined Effects AMR Simulations with Enzo (Mesinger, Bryan & Haiman 2007) - (1 h -1 Mpc) 3, root grid, run from z=99 to z=15 - re-simulate inner (0.25 h -1 Mpc) levels of refinement h -1 pc resolution at z=20 - biased (2.4  ) region, yields several hundred DM halos in mass range of 10 5 M  <M<10 7 M  Examine Effects of Transient Photoheating - J(UV) = 0 (test run) - Flash ionization (c.f. O’Shea et al. 2006) - J(UV) = 0.08 or 0.8 for  t = 3  10 6 years (uniform, opt.thin) Examine Effect of Constant LW background < J(LW) < added to J(UV)=0 and 0.8 runs

Cold gas develops in a cooling time  t = t cool ∝ T / n gas x H2 Works on halo-by-halo basis - near cancelation T: varies little (initial Compton cooling) n gas : depressed by factor of ~ 40 x H2 : increased by factor of ~ 10 net delay: factor of ~4 Adding Lyman-Werner background ( eV) t(photo-dissociation) ~ t(formation) Delayed Cooling

Radiative Feedback Simulation Summary H 2 cooling in minihalos is strongly suppressed H 2 cooling in minihalos is strongly suppressed for a soft UV background of for a soft UV background of J(LW) ≳ 0.01  erg s cm -2 Hz -1 sr -1 J(LW) ≳ 0.01  erg s cm -2 Hz -1 sr -1 Transient UV photo-heating strengthens negative Transient UV photo-heating strengthens negative feedback near sources, where flux is feedback near sources, where flux is J(UV) ≳ 0. 1  erg s cm -2 Hz -1 sr -1 J(UV) ≳ 0. 1  erg s cm -2 Hz -1 sr -1 Smallest halos with M ~ 10 6 most vulnerable Smallest halos with M halo ~ 10 6 M ⊙ most vulnerable Feedback switches from UV to LW at ~100 Myr Feedback switches from UV to LW at ~100 Myr For comparison, flux needed to ionize universe is For comparison, flux needed to ionize universe is J(ion)  10  erg s cm -2 Hz -1 sr -1 J(ion)  10  erg s cm -2 Hz -1 sr -1 Feedback retards reionization when f ion ≳ 0.1-1%

Many pieces of evidence that bright quasar phase is short: — 10 7 years ≲ t Q ≲ 10 8 years (e.g. Martini 2004) Fiducial recombination time in z>6 IGM: — t rec ≈ t Hubble ≈ 5  10 8 years at mean density at z=8 — fossils outnumber active bubbles by factor t rec /t Q ≈ 5-50 Fossils affect the IGM, and are useful probes: — large (40-50 comoving Mpc), prime targets for 21cm imaging — probe quasar properties (Wyithe, Loeb & Barnes 2005; Zaroubi & Silk 2005; Kramer & ZH 2007) — probe IGM properties (Lidz et al., Alvarez & Abel, Geil & Wyithe) — entropy floor even in recombined fossils (Oh & ZH 2003) — H 2 formation (Ricotti et al. 02; Kuhlen & Madau 05; Mesinger et al. 07) Fossil Quasar Bubbles

Recombination must be inhomogeneous: — over-dense regions recombine quickly — under-dense regions remain ionized for longer than t rec Pre-existing galaxies: — mean free path in fossil starts much higher than outside — can pre-existing galaxies keep most of the fossil ionized? (easier than to ionize the region to begin with) How do we distinguish fossils? — “grey” bubble: reduced contrast relative to active bubbles but ionization nearly uniform — large size distinguishes them from rare large galaxy-bubbles How does HII region recombine? Furlanetto, Haiman & Oh (2008)

Fossil Recombination With Zero Flux Assume  bg =0 Follow  -dependent recombination cf: equivalent  crit with P(  ) from MHR00 Miralda-Escude, Haehnelt & Rees (2000) Compute m.f.p. (including the under-dense voids) m.f.p. remains ~Mpc if x HI ≲ (at  ~1) z=14 z=6 z=9

Fossil Evolution vs Global Reionization Semi-analytical reionization model Follow mean  x HI  in z=10 fossil vs globally Additionally: follow  -dependent x HI inside fossils Compute m.f.p. using MHR00 c.f. clustering length of pre-existing galaxies uniform, high ionization

An Early Fossil (z=15) Probably much rarer than fossils from z=10 Still remains highly ionized different from z=10 fossil: m.f.p. drops below galaxy clustering length will develop (reduced contrast) swiss-cheese

Check validity of MHR00 m.f.p. Assume uniform  bg neglect self-shielding Compute optical depth  across one MHR00 m.f.p., including the under-dense voids z=10 fossil: x HI ≲  =0.9, 0.5, 0.4 z=15 fossil:  =13, 4.5, 1.5, 0.7, 0.1 z=14 z=7 z=9

Implications Fossils outnumber active bubbles, last longer than t(rec) Fossils produced at z ≲ 10 remain highly and uniformly ionized “grey zones”: look similar in 21cm to active bubbles, but with a reduced contrast Example:  X HI  ~ 10-20% in fossil, 70-80% outside. Nearly uniform ionization in fossil, swiss-cheese outside. Analogous fossils expected during helium reionization Makes “double-reionization” difficult to arrange