Supermassive Black Holes in Galactic Nuclei

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Supermassive Black Holes inGalactic Nuclei

• Xue-Bing Wu (???)
• (Dept. of Astronomy, Peking Univ.)
• wuxb_at_bac.pku.edu.cn

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Content

• 1 Black holes in the universe
• 2 Supermassive black holes in active galactic
  nuclei
• 3 Recent progress in AGN BH mass study
• 4 Summary discussion

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Brief history of black hole concept

• 'Black hole' in classical physics
• Dark star was suggested in 1783 by John
  Mitchell.
• It was rejected soon in 1808 because of Thomas
  Youngs light interference experiment.
• 'Black hole' in modern physics
• General relativity predicted it Schwarzschilds
  singularity.
• Einstein rejected it for philosophical reasons.
• Chandrasekhars white dwarf mass limit demanded
  it.
• Eddington rejected it, again for philosophical
  reasons.
• Oppenheimers neutron star mass upper limit
  demanded it.
• Wheeler rejected it, and again for philosophical
  reasons.
• Wheeler was finally convinced of it and named it
  BLACK HOLE in 1967.
• Black hole physics finally got off-ground since
  then.

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1. BHs in the universe

• Three categories of astrophysical BHs
• Primordial BHs M1015g, not detected yet
• Stellar-mass BHs M3-20 solar masses, 20
  detected in BH X-ray binaries
• Supermassive BHs M106-109 solar masses, exist
  in the center of galaxies
• Intermediate-mass BHs M102-104 solar masses
  (??)

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Primordial Black Holes Basic Properties

• Proposed by S. Hawking
• Mass 1015 grams
• Lighter ones already died
• Radius 10-13 cm
• Density 1053 grams/cm3
• Temperature 1012 K
• Lifetime 1010 years
• Some are dying now
• Fate evaporation leading to final explosion
• Strong gamma-ray emission
• None observed yet!

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An Example of Stellar-mass BH Cyg X-1
Mass function
Cyg X-1
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Supermassive Black Holes in Nearby Galaxies

• (Kormendy Richstone 1995 Kormendy Gebhardt
  2001 Ho 1999)
• Stellar dynamics
• Mass determined by the rotational velocity V and
  the velocity dispersion ? of stars
• Gas dynamics
• Keplerian rotation of ionized gas in a disk-like
  configuration
• Water maser dynamics
• 22 GHz microwave emission from extragalactic
  water masers

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Stellar Dynamics
NGC 3115 (Kormendy et al. 1996) M2E9 Msun 25
times massiver than the visible star cluster
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Stellar Dynamics
Our Galaxy (Genzel et al. 1997 2003) M(34) E6
Msun
Stellar velocity proper motions around Sgr A
yield a BH mass of (34) 106 Msun
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Gas Dynamics

• Optical emission lines
• M87 H, NII
• M2.4E9 Msun

Macchetto et al. (1997)
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Water Maser Dynamics

• Radio masers
• 22 GHz microwave emission from extragalactic
  water masers
• VLBA resolution 0.0006as

NGC 4258 M4E7 Msun
Miyoshi et al. (1995)
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Determination of Supermassive black hole masses
in the center of galaxies (Kormendy Gebhardt
2001)
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2 Supermassive Black Holes in Active Galactic
Nuclei (AGN)
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What makes AGN interesting?

• Prodigious luminosity (1E46erg/s) emitted in a
  tiny volume (ltpc3) over an extraordinary broad
  range of frequencies, displaying strong emission
  lines whose widths suggesting velocities ranging
  up to 10000 km/s

AGN Zoo Seyfert Galaxies Quasars Radio
Galaxies Blazars (BL Lacs OVVs) LINERs and
ULIRGs
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Variabilities
Spectra
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Examples of quasars identified by ourselves (Wu,
Bade Beckmann, 1999, AA, 347, 63)
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Central engine of AGNs

• Supermassive black hole
• Accretion disk
• Broad line region
• Dusty torus
• Narrow line region
• Jet

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• Black hole mass estimations of AGNs
• Direct methods
• Stellar dynamical studies not feasible in AGN,
  since the AGN outshines the stars.
• Can use gas kinematics, if the gas is seen in
  Keplerian rotation. In M87, r75 pc disk (NOT
  Accretion Disk) yields 3 109 Msun, ?gt107 Msun
  pc-3
• Megamasers in edge-on nuclear gas disks Sy2
  NGC4258, 0.02 pc resolution gives perfect
  Keplerian rotation (pt mass), 3.6 107 Msun, ?gt5
  1012 Msun pc-3 proper motions radial
  accelerations also measured, allowing a distance
  determination to be made

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Indirect Methods

• Accretion disks fitting of the big blue bump in
  the spectra of AGN
• Standard thin disk model (Shakura Sunyaev 1973)

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Accretion disk fitting of the big blue bump in
the spectra of AGN evidence for AD (Sun Malkan
1989)
NGC 5548
AD model fits suggest 108-9.5 Msun for quasar,
107.5-8.5 Msun for Sy1s, plus mass accretion
rates 0.1-1 and 0.01-0.5 times Eddington
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Broad gravitational-redshifted Iron K? line of
Seyfert 1 galaxies--accretion disk modeling
Tanaka et al. (1995) Nandra et al. (1997)
Fabian et al. (1989)
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Reverberation mapping from optical variability
Peterson (1997)

• Broad emission line region 0.01 - 1pc
  Illuminated by the AGN's photoionizing continuum
  radiation and reprocess it into emission lines
• RBLR estimated by the time delay that corresponds
  to the light travel time between the continuum
  source and the line-emitting gas RBLR c ? t
• V estimated by the FWHM of broad emission line

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Determination of Supermassive black hole masses
of AGN with reverberation mapping
Kaspi et al. (2000)
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BLR Scaling with Luminosity

• To first order, AGN
• spectra look the same

• Same ionization
• parameter
• Same density

With the R-L relation, one can estimate the BLR
size from the optical continuum luminosity
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SMBH and Galactic Bulge

• Relations of black hole mass with bulge
  luminosity and central velocity dispersion (for
  normal galaxies AGNs)

AGN
Ferrarese et al. (2001)
With the M-s relation, one can estimate the BH
mass from the stellar velocity dispersion
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Methods of estimating SMBH Masses
Low-z AGNs
Peterson (2004)
High-z AGNs
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3. Recent progress in AGN BH mass study
1. On black hole masses, radio loudness and bulge
luminosities of Seyfert galaxies, Wu Han
2001, AA, 380, 31 2. Inclinations and black hole
masses of Seyfert 1 galaxies, Wu Han 2001,
ApJ, 561, L59 3. Supermassive black hole masses
of AGNs with elliptical hosts, Wu, Liu, Zhang
2002, AA, 389,742 4. Black hole mass and binary
model for BL Lac object OJ 287, Liu Wu
2002, AA, 388, L48 5. Black hole mass
estimation with a relation between the BLR size
and emission line luminosity of AGN, Wu, Wang,
Kong, Liu, Han 2004, AA, 424, 793 6. Black
hole mass and accretion rate of AGNs with
double-peaked broad emission line, Wu Liu
2004, ApJ, 614, 91
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(1) Estimation of BH masses of Seyfert galaxies
(Wu Han 2001, AA, 380, 31)

• Sample of Seyfert galaxies
• 37 Seyferts (22 Sy 1s, 15 Sy 2s) with measured
  MBH or ? from two bright Seyfert samples
• Palomar B lt 12.5 mag, 49 Seyferts (21 Sy 1s, 28
  Sy 2s)
• 21 Sys selected (13 Sy 1s, 8 Sy2s)
• CfA Zwicky magnitude lt14.5, 48 Sys (33 Sy 1s, 15
  Sy 2s)
• 23 Sys selected (15 Sy 1s, 8 Sy2s), 8 common with
  Palomar sample
• 5 Sys with dynamical measured MBH, 10 Sy 1s with
  MBH measured by reverberation mapping
• 22 Sys with measured ? but unknown MBH

(M-s relation applies here!)
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Sample of Seyfert galaxies
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Relation of radio power with SMBH masses
Correlation between BH mass and bulge magnitude
MVbulge -11.01 -1.22 log (MBH /Msun )
gt MBH ? Mbulge1.74 a non-linear relation!
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(2) Determing the BLR inclination of Seyfert 1
galaxies based on BH mass estimations (Wu Han
2001, ApJ, 561, L59)

• BLR dynamics (Wills Browne 1986)
• Virial BH mass
• BH mass-velocity dispersion relation (Gebhardt et
  al. 2000)

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Inclinations of BLR in Seyfert galaxies
Mean value of 36 degree, supporting the AGN
unification scheme!
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Inclinations of BLR in Seyfert galaxies
NLS1
Inclination affects the line width NLS1s seem to
have smaller BH masses.
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• (3) SMBH Mass of AGNs with elliptical host galaxy
• (Wu, Liu Zhang, 2002, AA, 389, 742)
• Reverberation mapping can not apply to BL Lacs
  Only 10 BL Lacs have measured ? values (Falomo et
  al. 2002 Barth et al. 2002)
• Host galaxies of BL Lacs are ellipticals (Urry et
  al. 2000)
• ? values can be derived based on the fundamental
  plane of ellipticals then SMBH masses could be
  estimated for BL Lacs with high-quality images

(Bettoni et al. 2001)
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• Comparison of Eddington ratios of AGNs

The Eddington ratios (dimensionless accretion
rates) of radio galaxies are about two orders
lower than those of quasars.
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(4) Black hole mass and binary BH model for BL
Lac object OJ 287 (Liu Wu, AA, 2001, 388, L48)

• OJ 287, one of the best studied BL Lacs with
  optically outbursts recurrent with a period of
  11.65 year (Sillanpaa et al. 1988).
• A predicted optical outburst in 1994 was
  observed and a binary black hole model is favored
  (Lehto Valtonen 1996).
• The previous binary BH model requires the
  primary BH mass of 1.5E10 solar masses (Pietila
  1999), which is much larger than the estimated BH
  masses of other BL Lac objects.
• A new binary BH model (Valtaoja et al. 2000) with
  BH mass lt1E9 solar mass can explain the observed
  double-peaked outburst behavior.

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(Valtaoja et al. 2000)
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Primary black hole mass of OJ 287 The host
galaxy was marginally resolved of an effective
radius re0.72 and R-band absolute magnitude
MR -23.23 (Heidt et al. 1999) Using the BH mass
bulge luminosity relation (McLure Dunlop
2002), It gives MBH4.6E8 solar masses. Using
the fundamental plane and the MBH - ?
relation, It gives MBH3.2E8 solar masses. ?
MBH4E8 solar masses ? Support the new binary BH
model (Valtaoja et al 2000)
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(5) AGN BH Mass estimation with the R-LH?
relation (Wu, Wang, Kong, Liu Han 2004, AA,
424, 793)

• BLR sizes are usually derived previously from
  the empirical relation R? L5100A0.7(Kaspi et al.
  2000). Can it apply to RL AGN?
• Optical jets of some AGNs have been observed by
  the HST (Scarpa et al. 1999 Jester 2003 Parma
  et al. 2003). Optical Synchrotron radiations have
  been found in some RL AGNs (Whiting et al. 2001
  Chiaberge et al. 2002 Cheung et al. 2003)

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• For RL AGNs, optical continuum luminosity may be
  significantly contributed from jets, and may not
  be a good indicator of ionizing luminosity
• Using the R-L5100A relation can overestimate MBH
  for radio-loud quasars
• It may be better to use the relation between the
  emission line luminosity and the BLR size

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Recently we also extended such a study to UV
broad emission lines (Mg II CIV) (Kong, Wu,
Wang, Han, 2006)
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(6) Black hole mass and accretion rate of AGNs
with double-peaked broad emission line(Wu Liu,
2004, ApJ, 614, 91)

• Double-peaked broad line AGNs are usually
  believed to be LINER-type low-luminosity ones (Ho
  et al. 2001)
• 150 double-peaked AGN discovered (SDSS and
  RLAGN) SDSS double-peaked AGNs 76 are
  radio-quiet, with medium luminosities (1E44
  erg/s) 12 are LINER (Strateva et al. 2003)
• With the R-L relation, we estimated the BH mass
  (from 3E7 to 5E9 solar masses) and the Eddington
  ratio (from 0.001 to 0.1) of 135 double-peaked
  AGNs.
• We found big blue bumps in some luminous
  double-peaked AGNs
• We suggested that for luminous double-peaked AGNs
  with Eddington ratio larger than 0.01, the
  accretion process is probably different from that
  of LINER-type double-peaked AGNs

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Black hole mass and accretion rate of AGNs with
double-peaked broad emission line
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4. Summary and Discussion

• Supermassive black holes with mass of 106 to 109
  solar masses exist in the center of both normal
  and active galaxies
• Direct dynamic methods of estimating the BH mass
  can only be applied to several nearby AGNs.
  Reliable BH mass of AGNs can be obtained by
  reverberation mapping, MBH - ? relation and two
  R-L relations.
• Estimating the BH mass is important and helpful
  to other studies on AGN and galaxy evolution

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Eddington ratio and accretion physics in
different types of AGN
From the BH mass, we can derive Eddington ratio (
Lbol/Ledd), which measures the accretion rate in
Eddington unit. Accretion disk structure is
strongly dependent on the accretion rate
Abramowicz et al. (1995)
SD Slim disk (Abramowicz et al. 1988) RTD, GTD
Radiation pressure and gas pressure dominated
thin disk (Shakura-Sunyaev 1973) SLE Hot,
two-temperature disk (Shapiro, Lightman Eardley
1976) ADAF Advection dominated accretion flow
(Narayan Yi 1994)
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Transition of different accretion modes as
accretion rate changes Applications in black hole
X-ray binaries (AGN too?)
Fender (2003)
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Knowing accretion rate may help us to understand
the broad line region physics of AGN
(Nicastro et al. 2003)
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Variations of broad line component at different
luminosity level
L
Broad line component of CIV line of NGC 4151
Kong, Wu, Wang, Liu Han (2006, AA)
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A fundamental plane of black hole
activity (Merloni et al. MNRAS, 2003)
Common physics in BH systems(?) BH, accretion
disk, jet
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BH fundamental plane from a uniform sample of
radio and X-ray emitting broad line AGNs
Wang, Wu Kong (2006, ApJ)

• Cross-identified RASS-SDSS-FIRST broad line AGNs
• Different slope between radio-quiet and
  radio-loud AGNs
• Beaming effect from the relativistic jet of RL
  AGNs can contaminate the BH fundamental plane
  relation

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Radio--X-ray correlation with different X-ray
origins (Yuan Cui 2005, ApJ)
Flat slope
Steep slope
Consistent with the results obtained with our
uniform sample!
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SMBH and Galaxy Formation

• Black hole formation is closely related to galaxy
  formation

Tremaine et al. (2002)
MBH ??4
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SMBH in highest redshift quasar (z6.4)
Supermassive black hole formed in the early
universe!
Willott et al. (2003) (UKIRT/UIST)
Barth et al. (2003) (Keck II/NIRSPEC)
FWHM(MgII)5500km/s? MBH2E9 Msun FWHM(CIV)9000km
/s? MBH6E9 Msun
FWHM(MgII)6000km/s? MBH3E9 Msun
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Rees flow chart for the formation of a very
massive black hole
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• How BHs grow to 109 solar masses before z6?
  Accretion or merging?
• Hierarchical growth of BH by merging and gas
  accretion can produce such a SMBH, if the seed BH
  can form at zgt10 (Haiman Loeb 2001 Volonteri
  et al. 2003, 2005)
• The initial seed BH (M100-200Msun) may be formed
  by collapse of massive first generation stars in
  the early Universe (Madau Rees 2001 Schneider
  et al. 2002)
• A single BH (M180Msun) at z20 could also
  produce a SMBH with M3 109Msun if it were
  constantly accreting at the Eddington luminosity
  with a radiation efficiency of 0.1 (Barth et al.
  2003).

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How growing BHs regulate galaxy formation
(Di Matteo et al. 2005, Nature)

• Black hole feedback
• When the galaxies and their black holes collide a
  quasar is ignited which expels most of the gas in
  a strong wind. The remaining galaxy contains very
  little gas but a large supermassive black hole.
  The black hole mass is related to the size of the
  galaxy in agreement with observations.

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Future Efforts
Detecting the gravitational wave produced by
coalescing BHs with Laser Interferometer Space
Antenna (LISA, 2010?)
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Chinese Facilities in the Near Future
LAMOST The Large Sky Area Multi-Object Fiber
Spectroscopic Telescope The optical
spectroscopic survey carried out by LAMOST of
tens of millions of galaxies and others will make
substantial contribution to the study of
extra-galactic astrophysics and cosmology, such
as galaxies, quasars and the large-scale
structure of the universe.
The project will come into operation at the end
of 2007.
http//www.lamost.org
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Chinese Facilities in the Near Future
FAST (Five hundred meter Aperture Spherical
Telescope) The largest single dish radio
telescope in the world
http//www.bao.ac.cn/bao/LT/
HXMT (Hard X-ray Modulation Telescope)
http//www.hxmt.org
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Have fun with black holes !
Thank you