Growth & implications of black holes at z > 6 Martin Rees (+ Marta Volonteri)
Massive black holes? Giant Ellipticals/S0s Spirals Dwarfs Globular Clusters Yes Yes but black hole Some Maybe mass scales with at least bulge mass not total mass
Is this really tighter? Kormendy 2003 bulge mass black hole mass scales with stellar velocity dispersion of the bulge
A very early assembly epoch for QSOs QSOs A very early assembly epoch for The very high redshift quasar SDSS 1148+3251 at z=6.4 has estimates of the SMBH mass M BH =2-6 x10 9 M sun (Willott et al 2003, Barth et al 2003) As massive as the largest SMBHs today, but when the Universe was <1 Gyr old!
THE HIGHEST-REDSHIFT QUASARS Becker et al. (2000)
What happens earlier? • What are the ‘hosts’ of the first holes? • How massive are these ‘seed holes’ (stellar - -- Pop III remnants -- or ‘intermediate’) ? • How fast can they grow via: (a) accretion? (b) mergers? How can we probe the highest redshifts (detection, environmental impact, ‘fossils’)?
First “ “Population III Population III” ” Stars? Stars? First Hierarchical Galaxy Formation: small scales collapse first and merge later to form more massive systems BARYONS: need to COOL COOL First ‘action’ happens in the the smallest halos with deep enough smallest halos with deep enough potential wells to allow this potential wells to allow this (at z~20-30) (at courtesy of M. Kuhlen
Swift
HOW can you make a (super)massive black can you make a (super)massive black HOW hole @ z � � 10-30? 10-30? hole @ z M BH ~ 100-600 M sun M BH ~ 10 3 -10 5 M sun PopIII stars remnants Viscous transport (e.g. Haehnelt & Rees 1993, Eisenstein & Loeb 1995, Bromm & Loeb (Madau & Rees 2001, 2003, Koushiappas et al. 2004) Volonteri, Haardt & Madau 2003) � Simulations suggest that the first � Efficient viscous angular momentum stars are massive M ~ 100-600 M sun transport + efficient gas confinement (Abel et al., Bromm et al.) � Metal free dying stars with Bar-unstable self-gravitating gas (Begelman, Volonteri & Rees 2006) M>260M sun leave remnant BHs � Transport angular momentum on the with M seed � 100M sun (Fryer, Woosley & Heger) dynamical timescale, process cascades
The seeds at z>20 are small, ~ 100-10 5 5 M M sun The seeds at z>20 are small, ~ 100-10 sun How do MBH seeds grow to become supermassive e? How do MBH seeds grow to become supermassiv BH-BH mergers vs gas accretion gas accretion BH-BH mergers courtesy of L. Mayer Total mass density in MBHs is Total mass density in MBHs grows almost constant in time: just with time reshuffle the mass function
Supermassive holes grow from seed seed pregalactic BHs. . These seeds are incorporated in larger and larger halos, accreting gas and dynamically dynamically accreting gas interacting after mergers. interacting All models for first BHs predict a biased formation: in the HIGHEST PEAKS OF DENSITY HIGHEST PEAKS OF DENSITY FLUCTUATIONS at z~20-30 FLUCTUATIONS
Formation and evolution of supermassive binaries 1. Dynamical friction t � a 2. Binary hardening due to stars or accretion of gas 3. Gravitational radiation t � a 4 Do they merge?
LISA Will see mergers of 10 5 –10 7 Msol black holes 2015+?
Lisa sensitivity to massive black hole binaries
Gravitational rocket Gravitational rocket binary center of mass recoil during coalescence due to binary center of mass recoil during coalescence due to asymmetric emission of GW asymmetric emission of GW (e.g. Baker et al 2007, Campanelli et al 2007, Gonzalez et al 2007) v esc from today v esc from today � � ESCAPE VELOCITY: galaxies galaxies ELLIPTICAL GALAXIES DWARF GALAXIES/ v esc from high-z v esc from high-z � � MINIHALOS proto-galaxies proto-galaxies
Gravitational rocket Gravitational rocket at at z >10 z >10 more than more than 50 -80% 50 -80% of merging MBHs can be of merging MBHs can be kicked out kicked out of their halo of their halo (Volonteri & Rees 2006, Volonteri 2007) the gravitational gravitational the rocket effect can be a effect can be a rocket threat at the highest at the highest threat redshifts, much less redshifts, much less so at low-z so at low-z
Build-up of holes by accretion Build-up of holes by accretion continuous gas supply from host halo? (a) Is there a continuous gas supply Johnson & Bromm 2007, Pelupessy et al. 2007 super-critical : is ’excess’ radiation (b) When supply is super-critical trapped and/or accretion inefficient, allowing rapid growth in hole’s mass ? Volonteri & Rees 2005 Or is there a radiation-driven outflow? Wang et al. 2006 Wang et al. 2006 influence of spins ? affect maximal (c) What is the influence of spins accretion efficiency, importance of Blandford-Znajek energy extraction, etc
High spin high radiative efficiency Schwarzschild: spin=0 � =0.06 maximally rotating: spin=0.998 � =0.31 Since for a BH accreting at the Eddington rate the time required to reach a final mass scales as: SDSS 1148+3251 � =0.06 � Small radiative efficiency � � =0.3 M fin /M in ~ 10 5 , � ~ 0.1 ⇒ t acc =0.6 Gyr � Large radiative efficiency � M fin /M in ~1 0 5 , � ~ 0.3 ⇒ t acc =2.2 Gyr
High-z MBH spins High-z MBH spins � mergers can spin BHs either up or down in a sort of random walk Hughes & Blandford 2003 � accretion spins MBHs up via spin/disc coupling if M acc � M BH Moderski & Sikora 1996, Volonteri, Madau, Quataert & Rees 2005 High-z MBHs increase their mass by several High-z MBHs increase their mass by several orders of magnitude in a short time! orders of magnitude in a short time! Rapidly growing MBHs likely have spins MBHs likely have spins close to maximal close to maximal Schwarzschild: spin=0 � =0.06 tacc=0.6 Gyr maximally rotating: spin=0.998 � =0.31 tacc=2.2 Gyr
Fabian et al 02 XMM
NOTE; Classic argument of Soltan (1982), which compares total mass of holes with total radiative output, implies that most of the mass is gained via ‘efficient’ accretion. But most ot the ‘e-folds’ (eg first 10% of mass) could be gained rapidly via inefficient accretion � qso(0) =2.1x10 5 [0.1(1- � )/ � ]M � Mpc -3 � SMBH =2.5-3.5x10 5 M � Mpc -3 � � ~0.2 @ z<5 Elvis, Risaliti & Zamorani 2002 from Yu & Tremaine 2002
EM bands: X-ray and NIR EM bands: X-ray and NIR soft X– –ray band [0.5 ray band [0.5– –2 keV] 2 keV] soft X > 10 � 1 � 17 7 erg s erg s � 1 � 1 cm cm � 2 � 2 (XEUS) (XEUS) > 10 N(z) (deg -2 ) >8 Ms CDF-N >8 Ms CDF-N NIR fluxes above the NIR fluxes above the planned JWST sensitivity planned JWST sensitivity soft X– –ray band [0.5 ray band [0.5– –2 keV] 2 keV] 6 7 redshift 9 10 11 soft X > 10 � 1 � 16 6 erg s erg s � 1 � 1 cm cm � 2 � 2 > 10 2 2-5 CDF-N � CDF-N � 170 arcmin 170 arcmin 2 2-5 sources sources cfr Koekemoer et al. 2003 Salvaterra, Haardt & Volonteri 2006 Future instruments can “ “easily easily” ” detect the early detect the early Future instruments can stages of MBH evolution stages of MBH evolution
“Environmental impacts” of Pop III remnants and black holes at z > 6
X-Rays from low and intermediate mass BHs • � Overall efficiency of accretion exceeds nuclear level. • Accreting BHs emit a significant fraction of their energy in X-rays. • X-rays have a mean free path longer than the non-linear cosmic length scale. • X-ray ionization is “inside out”, with low density regions (partially) ionized first - minimizing recombination losses. • => Ionization from accreting BHs is efficient.
Diffusion of flux? How did the flux generated by the jets in Cygnus A or by the pulsar in the Crab Nebula diffuse into ambient or embedded thermal plasma (to the extent indicated by Faraday rotation)?
Production and diffusion of: ‘metals’ <====> ‘seed’ B-field (Filling factor? Distribution in IGM? Fine-grained mixing?)
• At z=1000 the Universe has cooled down to 3000K . Hydrogen becomes neutral (“Recombination”). • At z < 20 the “first” star (clusters)/small galaxies form. • At z ~ 6-20 these gradually photo-ionize the hydrogen in ~ the IGM (“Reionization”). • At z<6 galaxies form most of their stars and grow by merging. • At z<1 massive galaxy clusters are assembled.
Key issues • Were SMHs ‘seeded’ by Pop III remnants, or by ‘intermediate mass’ holes? • How can we detect individual objects out to z=20? • What is the ‘environmental impact’? (first ‘metals’, magnetic fields, ionization, etc etc) • What is relative importance of mergers and accretion (GR very important!)?
Recommend
More recommend
