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2003 Birth and Dynamics of Galactic Black Holes • Demography of quiescent black holes in the present-day universe • Demography of accreting black holes (quasars) at early cosmic times • Dynamics of black holes in galactic centers: Brownian motion, binaries • Effects of quasars on their cosmic habitat Collaborators: Rennan Barkana, Volker Bromm, Pinaki Chatterjee, . . Lars Hernquist, Stuart Wyithe The Black Hole in the Galactic Center: SgrA* VLT with Adaptive Optics •“3-color”: 1.5 - 3 um • 8.2 m VLT telescope • CONICA (IR camera) • NAOS (adaptive optics) • 60 mas resolution Stellar Positions & Motions Reid et al. 2002 SgrA* in July 1995 Where was Sgr A* in May‘02? • Sgr A* position: 10 mas • Star “S2” seen at pericenter V ~ 5000 km/s ! Orbit determined S2’s orbit • 15 year period • e = 0.87 • Pericenter 15 mas = 120 AU . = 17 light-hours (Schoedel et al 2002) Ghez et al. 2003 SO-16 closest approach at 90 AU Simultaneous fit of orbits implies: 1. BH mass: (4 æ 0:3) â (d=8kpc) 3 â 106M ì 2. BH proper motion: < 0.8+-0.7 mas/yr Feeding SgrA* with Stellar Winds Emission region: ð ñ ï J < J max = ñ 4GM c Loeb, astro-ph/0311512 Sgr A*’s motion • Continues along Galactic Plane • Remove Sun’s motion V(Sgr A*) < 7 km/s Reid et al. (2002) Lower Limit on Sgr A*’s Mass • Backer & Sramek (1999): MV2 ~ mv2 <energy> • Reid et al (1999): MV ~ mv <momentum> • Chatterjee, Hernquist & Loeb (2002) mass estimator: a <energy> Mlim ~ G M(R) m / R V2 • V < 2 km/s a M > 106 Msun Apparent Deviations from Keplerian Orbits dt obs = (1 + vk=c)dt Doppler transformation of time: a? ;obs = d 2x ? dt 2obs = (1 à 2v k ) c a? à v? a c k BH star v c ø 10à 2 at ø 100A:U: Loeb 2003 (astro-ph/0309716) Probing the Spacetime Around SgrA* with Pulsars ~10-100 massive stars with P<100 yr and lifetime of ~ 107 years ~1000 NS in steady state 1-10 detectable pulsars at 10-20 GHz • BH spin vector from frame-dragging + imaging of pulsar orbit • Inner stellar cluster from gravitational scattering events • Test accretion flow models by measuring plasma density Pfahl & Loeb 2003 (astro-ph/0309744) Enclosed Mass Schoedel et al. 2002 Water Masers: NGC 4258 Moran, Greenhill, & Herrnstein (2000) Keplerian Velocity Profile Miyoshi et al. 1995 Mass densities Object Density Method (Msun/pc3) M 87 NGC 4258 Sgr A* Sgr A* 2 x 106 7 x 109 8 x 1015 2 x 1021 HST: 3x109 Msun in 7 pc VLBA : H2O 3x107 Msun in 0.1 pc S16’s orbit 3x106 Msun in 90 AU Sgr A*s p.m. 1x106 Msun in 1 AU SMBH 5 x 1025 Rsch 3x106 Msun in 0.05 AU Correlation between black hole mass and velocity dispersion of host stellar system ì = 4:02 æ 0:32; ë ì = 4:02 æ 0:32; ë = 8:13 æ 0:06 Tremaine et al. 2002 ì = 4:58 æ 0:52 ë = 8:22 æ 0:07 Ferrarese 2002 log(M =M ì ) = ë + ì log(û ?=200km=s) Quasars Reside in Galaxies Archeology of the Universe Earth distance The more distant a source is, the more time it takes for its light to reach us. Hence the light must have been emitted when the universe was younger. By looking at distant sources we can trace the history of the universe. Quasars already exist at z~6, only a billion years after the big bang! Becker et al. 2001 The Earliest Quasar Detected: z=6.43 Fan et al. 2002 Cosmological Infall Around Quasars at z>6 Barkana & Loeb, Nature, 2003 Lya Line of Quasars SDSS (Vanden Berk et al. 2001) HST (Telfer et al. 2002) ROSAT (Yuan et al. 1998) Quasar spectrum ð 8 M BH = 10 M ì VC 300 km=s ñ5 Ferrarese et al. 2002 Tremaine et al. 2002 Wyithe & Loeb 2002 z = 4:80 M BH = 4:6 â 108M ì M = 2:5 â 1012M ì z = 6:28 M BH = 1:9 â 109M ì M = 4:0 â 1012M ì SDSS 1122 à 0229 SDSS 1030 + 0524 SDSS 1122 à 0229 SDSS 1030 + 0524 SDSS 1122 à 0229 SDSS 1030 + 0524 Basic Facts About the Universe • On large scales our universe is simple: HOMOGENEOUS: the same everywhere HOMOGENEOUS Observer 1 Observer 3 Observer 2 ISOTROPIC: the same in all directions Direction1 Direction 2 Earth Direction 3 But on small scales the universe is clumpy Early times Mean Density Intermediate times Late times Formation of Massive Black Holes in the First Galaxies õ = 0:05 H 2 suppressed Add Bromm R < 1pc M 1 ø 2:2 â 106M ì M 2 ø 3:1 â 106M ì Low-spin systems: Eisenstein & Loeb 1995 Numerical simulations: Bromm & Loeb 2002 Eddington Limit Gravitational force per proton: GM m p=r BH gas 2 Radiation force per electron: accretion 2 (L =4ùr c)û T For a spherical geometry, the outward radiation force balances the inward gravitational force at the Eddington luminosity: L E = (4ùGM m pc=û T) = 1:4 â 1046(M =108M ì )erg=s Accretion of fuel is possible only if L < LE Self-regulation of Supermassive Black Hole Growth quasar L t dyn ø 32M gasû 2 halo velocity dispersion maxf L g = L E / M bh dynamical time of galactic disk ! M bh 108M ì After translating û ! û? ð = 1:5 ñ5 û 200km=s this relation matches the observed M à û ã correlation in nearby galaxies (Tremaine et al. 2002; Ferarrese & Merritt 2002) Silk &Rees 1998; Wyithe & Loeb 2003 Quasar Luminosity Function Simple physical model: *Each galaxy merger leads to a bright quasar phase during which the black hole grows to a mass M ï / v5c and shines at the Eddington limit. The duration of this bright phase is proportional to the (smaller than unity) mass ratio in the merger. *Merger rate: based on the extended Press-Schechter model in a LCDM cosmology. duty cycle ~10 Myr Wyithe & Loeb 2002 Did the most massive galaxies form at z>6, only a billion years after the Big-Bang? Stars=collisionless fluid late accretion Core of CDM halos stabilizes at z~6 Loeb & Peebles 2002 Proposal confirmed by N-body simulations Gao Liang & Simon White (2003) Loeb & Peebles 2002 Brownian Motion of a Massive Black Hole in a Stellar System For a non-Maxwellian distribution function of stars the black hole is not in strict equipartition Chatterjee, Hernquist, & Loeb 2001 (ApJ, PRL) Black Hole Binaries due to Galaxy Mergers X-ray Image of a binary black hole system in NGC 6240 10kpc z=0.025 Komossa et al. 2002 Dynamics of black hole binaries R Figure1.ps Numerical experiment: 400,000 stars M/M*=0.25% Typical binaries coalesce in less than 10 Gyr due to wandering Chatterjee, Hernquist, & Loeb 2002 Open issue: kick velocity Laser Interferometer Space Antenna Gravitational Wave Amplitude from a Black Hole Binary at z=1 Gravitational Radiation from Coalescence of Massive Black Hole Binaries PULSARS LISA REDSHIFT FREQUENCY (Hz) Wyithe & Loeb 2002 Environmental Effects of Quasars Radiative: ionization of intergalactic hydrogen and helium Hydrodynamic: powerful relativistic outflows Spectrum of a High Redshift Quasar (z=5.73) Djorgovski et al. 2001, ApJL, submitted Transmitted flux ---> HI/HII<1e-6 (Fan et al. 2000) On the Threshold of the Reionization Epoch Djorgovski et al. 2001 Structure Formation in the IGM Density contrast of gas at z=0 for a 100x100x10 Mpc^3 slice Density contrast of gas shocked between z=0.14-0.09 Evolutionary Stages of Reionization • Pre-overlap • Overlap • Post-overlap neutral H Ionized H Reionization Histories of H, He Free Parameters: (i) transition redshift, z_tran, zt ran above which the stellar IMF is dominated by massive, zero-metallicity stars; (ii) the product of the star formation efficiency and the escape fraction of ionizing photons in galaxies, f escf ? . FILLING FRACTION H+ He+ REDSHIFT He++ Quasar model fits luminosity function data up to z=6 Wyithe & Loeb 2002 Quasars as Perturbers: Impact of Quasar Outflows on the IGM small-scale structure; magnetization; ionization BAL outflow jet Magnetized bubble quasar Intergalactic Medium (IGM) Is the IGM fully magnetized just like the ISM? Furlanetto & Loeb 2001 Volume Filling Factor of Quasar Bubbles Volume filling factor of IGM Magnetic energy density normalized by thermal at 10^4 K Probability Distribution of Bubble Magnetic Field *Could account for intra-cluster and galactic fields through B / ú2=3 adiabatic compression. Explains synchrotron halos of clusters. Injection of Positrons from AGN Jets e+ejet AGN Furlanetto& Loeb 2002 Spectrum of Positron Annihilation Line 3-photon decay of Positronium does not smear line due to keV temperature of cluster electrons (direct annihilation more probable) Line signal detectable with INTEGRAL (launched Oct. 2002) and EXIST (space station) for rich X-ray clusters out to 100 Mpc More details: ApJ, 572, 796 (2002) What fraction of the earliest quasars is being gravitationally lensed? - PS Halos - -No evolution OCDM LCDM SCDM Barkana & Loeb 2000 Are the Highest-Redshift Quasars Gravitationally Lensed? 4 SDSS Quasars with z>5.73 Observer Lensing Galaxy Quasar Wyithe & Loeb, Nature 2002 Time Delay = (gravitational +geometric) Excess magnification due to stars next to one of the images Magnifying the Broad Line Region of Quasars with Stellar Microlenses Quasar accretion disk Wyithe & Loeb 2002 (source of continuum emission) Observed Time-Delay Lightcurves RX J0911+05 SBS 1520+530 Burud et al. 2002 Anomalies of Time-Delay Lightcurves Observations: up to a few percent variations on tens to hundreds of days Observed anomalies in RX J0911+05 & SBS 1520+530 by Burud et al. (2002) ---> N<10^6 Lack of anomalies in Q2237+0305 ---> N>10^4 Inferred cloud number is consistent with bloated star model (Alexander & Netzer 1997) The Future of the Intergalactic Medium ÒË = 0:7; Òm = 0:3 (Recombination time)>>(Hubble time) outside collapsed objects today. This inequality will get much stronger in the future because the IGM density will be diluted exponentially with cosmic time. Future Evolution of Nearby Large-Scale Structure Coma Great Attractor Perseus Pisces Nagamine & Loeb 2002 The Long Term Future of Extragalactic Astronomy Accelerating source c us Loeb 2002, PRD; astro-ph/0107568 Analogy Ants = Photons Balloon=Expanding Space Analogy Ants = Photons Balloon=Expanding Space visited area (horizon) since blowing started (Big Bang) Analogy Ants = Photons Balloon=Expanding Space visited area (horizon) since the blowing began (Big Bang) Ants can be separated at a rate much larger than their own walking speed Maximum Visible Age All sources above a redshift of 1.8 are already out of causal contact with us! How many galaxes will reside within our event horizon in 100 billion years? Answer: one (the merger product of the Andromeda and Milky-Way galaxies) Ejection of Stelar Mass Black Holes from Globular Clusters star-star star-BH BH-BH ejection Chatterjee, Loeb & Haernquist 2003 Bright quasars reside in massive galaxies: Spectral Signature of Cosmological Infall Around the First Quasars infall observer accretion shock virialized gas redshifted accretion shock Barkana & Loeb, Nature, 2003; astro-ph/0209515 Simulation of Reionization z=11.5 Ionizing Background log(f_HI) Gnedin (2000) log T log(gas density) z=7 z=4.9 For comprehensive reviews on Reionization, see: *Barkana & Loeb 2001, Physics Reports 349, 125 *Loeb & Barkana 2001, ARA&A, 39 (Sep. 15) Collapse Redshift of Halos Atomic cooling H_2 cooling 1-sigma 2-sigma 2-sigma 3-sigma Probability Distribution of Bubble Radius *Magnetic pressure larger minimum b-parameter of Lya forest Redshift and Splitting Distributions of Lenses - LCDM z_s=5 z_s=2 - - OCDM … SCDM z_s=10 z_s=5 z_s=10 Flux from Lensing Galaxy in G-P Trough z_s~6 22.2 23.3 I*=22.2 SDSS at z=6.28 Alternative Interpretations of Lightcurve Anomalies (Gould & Miralda-Escude 1997) Hot spots in accretion disk Black Hole Hotspots: timescales are too short compared to observations! Second Alternative:Microlensing by Planets (Schild 1996) Accretion disk Motion in 10 years with a transverse velocity of 400 km/s Planets: (Also, timescales are too long! ruled out by the MACHO search). ü / ú2R 2 / (1 + z) 4 Spectrum of a Source Just Beyond the Reionization Redshift Absorption Spectrum A Simple Explanation Explain: binding enrgy per dynamical time Laser Interferometer Space Antenna (LISA) Future Prospects 3/2 • Vlim ~ 1/t • Mlim ~ 1/V2lim <energy> ~ t3 • When Vlim ~ 2 km/s (~2007), Mlim ~ 106 Msun • Could show ALL mass in Sgr A* ! Reid 2002