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Black Holes in the Universe Myungshin Im Astronomy Program, CEOU/Department of Physics & Astronomy, Seoul National University
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Black Hole: Infinite Abyss in Space-time Do They Really Exist?
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Quasar Im, Lee, et al. 2007, Lee, Im, et al. 2008 Quasars = QUASi-stellAR radio sources Peculiar radio stars, 3C48, 3C273: cosmological distance (1960, 1962, Bolton, Schmidt) 10 12 L ⊙ in a sphere with d < 10 12 km (light-month)
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Black Hole Star Cygnus-X1 Dark star around B-type star with strong X-ray emission ~15 M ⊙ BH (Orosz et al. 2011)
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BH Formation SN 2015F (Im et al. 2015, ApJS, youtube.com/watch?v=350HR7Z8OYw)
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Origin of Cosmic BHs Black holes with ~ a few M ⊙
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Stellar Mass Black Holes A few to 15 M ⊙ X-ray binary
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Galactic Center Ganzel et al., Also Ghez et al. 10 lt. days (0.2”) Black Hole ~ 4 million M ⊙
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How do we know? Direct measurement from stellar motion Gas motion at the center of galaxies Ghez et al. (UCLA) M BH = f*R*v 2 /G R: Orbital radius V: Orbital speed G: Grav. Const. f: Virial factor
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Supermassive Black Holes (SMBH) What are they? - Black Holes with masses ~ 10 6 – 10 10 M ⊙ Where are they ? - Centers of massive spheroids/bulges or quasars Elliptical galaxyBulges of SpiralsQuasars/AGNs
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Supermassive Black Holes in Inactive Galaxies SMBH mass ∝ mass, velocity dispersion, and luminosity of the host galaxy (e.g., Gebhardt et al. 2000; Ferrarese & Merritt 2000; Marconi & Hunt 2003) Marconi & Hunt (2003) But why? Which was born first? When did SMBHs appear Intermediate mass BHs? Galaxy Mass Black Hole Mass
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Making SMBHs Active Tidal Disruption Event, Swift J1644+57 Burrows, D., …, Im, M.,…et al. (2011, Nature)
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Black hole for Swift J1644+54 (Yoon, Im, et al. 2015) Long-term monitoring data host galaxy property M BH ~ a few x 10 6 M ⊙
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Feeding Materials to BH External Internal
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Galaxy merging as trigger (external mechanism) Black Hole Galaxy merging Merging features in Quasars! Hong & Im (2015) (e.g., Yoo et al. )
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Internal mechanism NGC 1365 (Barred spiral galaxy)
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Internal Mechanism? Cisternas et al. (2011) L > 10 45 erg/sec External L < 10 45 erg/sec Internal Still in debate
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Quasars (Active Galactic Nuclei) A few to hundred times brighter than host galaxy Nearly a point source can be detected at large distance Ideal tool for exploring cosmic history Nearly ~300,000 Quasars discovered so far (Paris et al. 2015)
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Reverberation Mapping Wavelength Flux Black Hole Mass: M = f*R*v 2 /G Broad Line Clouds Accretion Disc Emission line Continuum Variability in the Central Light Source Variability in the Line Flux Time Lag = Distance to Broad Line Clouds Width of the Emission Line Due to Doppler Motion = Velocity of BL Clouds
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Single Epoch Measurement Reverberation mapping Long-term monitoring needed (a few months – >10 years) R BLR ∝ L(Continuum) or Line Flux BH measurement with a single-epoch spectrum is possible ! (Kaspi et al. 2000; Vestergaard et al. 2005; Greene & Ho 2005; Kim, Im, & Kim 2010) Greene & Ho 2005 (Jun, Im, et al. 2015)
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When Did SMBHs Start to Form? The most massive SMBHs (M ~ 10 10 M ⊙ or more) at 2 < z < 4.5, 10 9 M ⊙ BHs at z ~ 7 (t univ ~0.8 Gyr) Shen et al. (2007), Also see Vestergaard et al. (2008) A few more points here from ground-based NIR spectroscopy (Jiang et al.; Kurk et al. 2007) UV line (less reliable) Optical line
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Can SMBHs Grow Fast? L= dE/dt = ε dM/dt M(t)=M(0) exp[(1-ε)/ε (t/t Edd )]=M(0) exp(t/τ), with τ ~ 4.5 x 10 7 (ε/0.1) yrs Not enough time (only ~0.5 Gyr between z= 7 and 15) ??? Volonteri & Rees (2006) Sijacki, Springel, & Haehnelt (2009) ε=0.1 ε=0.2 ε=0.4 Super-critical
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NIR Prism Observation AKARI Space Telescope
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BR 0006-6224 (z=4.51) NP NG
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SMBH Mass Evolution a few x 10 9 M ⊙ at z ~ 7 (0.7 Gyr) AKARI points (Jun, Im, et al. 2015) Quasar Cliff?
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Seed Black Holes Population III stars (M ~ 300 M ⊙ ): ~10 – 100 M ⊙ (Fryer, Woosely, & Heger, Bromm, Madau) Collapse of dense star clusters: ~ 1000 M ⊙ Direct collapse of proto-galactic gas: 1000-10 6 M ⊙ (Haehnelt & Rees 1993) Primordial Black Hole
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SMBH for Studying Early Universe
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High Redshift Quasar Selection with Special Filters Jeon, Im, et al. (2015)
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High redshift quasars have peculiar colors Kim, Im, et al. (2015) High Redshift Quasars
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IMS J2204+0111@z=6 Kim, Im, et al. (2015)
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Fan et al. (2006)
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What re-ionized IGM? Galaxies or Quasars?
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Many quasars: Quasars Few Quasars: Galaxies Quasar LF (Kim, Im, et al. 2015)
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Discovery of a Faint Quasar at z ~ 6
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What are the main sources that illuminated the early universe? Many quasars: Quasars Few quasars: Galaxies Quasar LF (Kim, Im, et al. 2015)
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Astrophysical Applications Re-ionization state of the universe Galaxy formation/evolution feedback mechanism Formation of the most massive structures in the universe large scale structures
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Summary Real BHs are discovered in 1960s Stellar mass, Supermassive, and Intermediate mass BHs (a few to 10 10 M ⊙ ) Seed BH mass /growth mechanism still uncertain Useful tool for studying the early universe
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