Black Holes in the Universe Myungshin Im Astronomy Program, CEOU/Department of Physics & Astronomy, Seoul National University

Black Hole: Infinite Abyss in Space-time Do They Really Exist?

Quasar Im, Lee, et al. 2007, Lee, Im, et al Quasars = QUASi-stellAR radio sources Peculiar radio stars, 3C48, 3C273:  cosmological distance (1960, 1962, Bolton, Schmidt) L ⊙ in a sphere with d < km (light-month)

Black Hole Star Cygnus-X1 Dark star around B-type star with strong X-ray emission ~15 M ⊙ BH (Orosz et al. 2011)

BH Formation SN 2015F (Im et al. 2015, ApJS, youtube.com/watch?v=350HR7Z8OYw)

Origin of Cosmic BHs Black holes with ~ a few M ⊙

Stellar Mass Black Holes A few to 15 M ⊙ X-ray binary

Galactic Center Ganzel et al., Also Ghez et al. 10 lt. days (0.2”) Black Hole ~ 4 million M ⊙

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

Supermassive Black Holes (SMBH) What are they? - Black Holes with masses ~ 10 6 – M ⊙ Where are they ? - Centers of massive spheroids/bulges or quasars Elliptical galaxyBulges of SpiralsQuasars/AGNs

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

Making SMBHs Active Tidal Disruption Event, Swift J Burrows, D., …, Im, M.,…et al. (2011, Nature)

Black hole for Swift J (Yoon, Im, et al. 2015) Long-term monitoring data  host galaxy property  M BH ~ a few x 10 6 M ⊙

Feeding Materials to BH External Internal

Galaxy merging as trigger (external mechanism) Black Hole Galaxy merging Merging features in Quasars! Hong & Im (2015) (e.g., Yoo et al. )

Internal mechanism NGC 1365 (Barred spiral galaxy)

Internal Mechanism? Cisternas et al. (2011) L > erg/sec  External L < erg/sec  Internal  Still in debate

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)

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

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)

When Did SMBHs Start to Form? The most massive SMBHs (M ~ 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

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

NIR Prism Observation AKARI Space Telescope

BR (z=4.51) NP NG

SMBH Mass Evolution a few x 10 9 M ⊙ at z ~ 7 (0.7 Gyr) AKARI points (Jun, Im, et al. 2015) Quasar Cliff?

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: M ⊙ (Haehnelt & Rees 1993) Primordial Black Hole

SMBH for Studying Early Universe

High Redshift Quasar Selection with Special Filters Jeon, Im, et al. (2015)

High redshift quasars have peculiar colors Kim, Im, et al. (2015) High Redshift Quasars

IMS Kim, Im, et al. (2015)

Fan et al. (2006)

What re-ionized IGM? Galaxies or Quasars?

Many quasars: Quasars Few Quasars: Galaxies Quasar LF (Kim, Im, et al. 2015)

Discovery of a Faint Quasar at z ~ 6

What are the main sources that illuminated the early universe? Many quasars: Quasars Few quasars: Galaxies Quasar LF (Kim, Im, et al. 2015)

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

Summary Real BHs are discovered in 1960s Stellar mass, Supermassive, and Intermediate mass BHs (a few to M ⊙ ) Seed BH mass /growth mechanism still uncertain Useful tool for studying the early universe