marianne vestergaard university of arizona
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First Steps Toward Constraining Supermassive Black-Hole Growth: Mass Estimates of Black Holes in Distant Quasars. Marianne Vestergaard University of Arizona. - PowerPoint PPT PresentationTRANSCRIPT
Collaborators: Alex Beelen, Misty Bentz, Frank Bertoldi, Chris Carilli, Pierre Cox, Xiaohui Fan, Shai Kaspi, Dan Maoz, Hagai Netzer, Chris Onken, Pat Osmer, Chien Peng, Brad Peterson, Rick Pogge, Gordon Richards, Francesco Shankar, Adam Steed, Fabian Walter, David
Weinberg
Marianne Vestergaard
University of Arizona
First Steps Toward Constraining Supermassive Black-Hole Growth:Mass Estimates of Black Holes in
Distant Quasars
Drexel University, February 10, 2006Drexel University, February 10, 2006
Active Galactic Nuclei• Bright galaxies with a point-
source of non-stellar activity in nuclei
• They are rare – comprise only a few percent of bright galaxies
• The most powerful are called quasars.
• Quasar nuclei outshine their host galaxy light
~10 17 cm -- scale of oursolar system
(Francis et al. 1991)
(Elvis et al. 1994)
Supermassive Black Holes
• How are their mass measured?
• How do they grow?
• How are black holes and galaxies connected?
Black Holes and Galaxy Formation
• Black holes are likely ubiquitous in galaxy centers• MBH – σ* relationship
The M – σ Relationship
(Tremaine et al. 2002; See alsoFerrarese & Merritt 2000; Gebhardt et al. 2000)
Black HoleMass
Bulge Velocity Dispersion
M σ4
• Black holes are likely ubiquitous in galaxy centers• MBH – σ* relationship
– Formation and evolution of bulges and black holes must be intimately connected
– When was it established? And how? – What came first, black hole or bulge (galaxy)?
• Black hole/star-formation feedback (theory)– Negative feedback kills star formation and black hole
growth by expelling gas (e.g., Springel, Di Matteo, & Hernquist 2005)
Black Holes and Galaxy Formation
(Springel et al. 2005)
Black holeactivity
Star formationactivity
Time (Gyr)
• Black holes are likely ubiquitous in galaxy centers• MBH – σ* relationship
– Formation and evolution of bulges and black holes must be intimately connected
– When was it established? And how? – What came first, black hole or bulge (galaxy)?
• Black hole/star-formation feedback (theory)– Negative feedback kills star formation and black hole
growth by expelling gas (e.g., Springel, Di Matteo, & Hernquist 2005)
– Positive feedback stimulate star formation (Silk 2005)
• Consequence: Galaxy bulges form later than supermassive black holes
Black Holes and Galaxy Formation
I. Black Hole Mass a. Determinationsb. Distributions
II. Black Hole – Galaxy Connection
III. Black Hole Evolution
Talk Outline
Talk OutlineI. Black Hole Mass
a. Determinationsb. Distributions
II. Black Hole – Galaxy Connection
III. Black Hole Evolution
mv2 – GmMBH /R = 0
Black Hole Mass
Mm
MBH = v2 R /G
Black Hole Mass
M
MBH = v2 R /G
Black Hole Mass
MBH = v2 R /GBlack Hole Mass
Insert figure from HST/ MW?
R
V
Why Study Quasar Black-Holes?
• Quiescent black holes (in normal galaxies) can only be studied in the nearby Universe
• Quasars are luminous and therefore ideal tracers of black holes to the highest observable redshifts
• Their host galaxies are prime targets for studying galaxy evolution in the early Universe
HST/STIS
8m telescope
30m telesc.
10010
Distance (Mpc)
(Ferrarese 2003)
109
108
Black Hole Mass
How Can MBH be Determined for Active Black Holes?
• Stellar kinematics
• Gas kinematics
• Reverberation mapping
(√)
(√)
√ √
Local Universe Higher-z
Possible Virial Estimators
Source Distance from central source
X-Ray Fe K 3-10 RS
Broad-Line Region 600 RS Megamasers 4 104 RS Gas Dynamics 8 105 RS Stellar Dynamics 106 RS
In units of the Schwarzschild radius RS = 2GM/c2 = 3 × 1013 M8 cm .
Mass estimates from thevirial theorem:
M = f (r V 2 /G)
wherer = scale length of regionV = velocity dispersionf = a factor of order unity, depends on details of geometry and kinematics
Note: the reverberation technique is independent of angular resolution
MBH = f v2 RBLR/G
Reverberation Mapping: RBLR= c τ
Virial Mass Estimates
t1 – t2 =
t = t1
t = t2
t = t3
t = t3 +
Reverberation Mapping Results
NGC 5548, the most closely monitored active galaxy
Continuum
Emission line
Light Curves
(Peterson et al. 2002)
MBH = f v2 RBLR/G
Reverberation Mapping:
–RBLR= c τ
• vBLR
Line width in variable (rms) spectrum
Virial Mass Estimates
t1– t2=
t = t1
t = t2
t = t3
t = t3 +
Reverberation Mapping
NGC 5548, the most closely monitored active galaxy
(Peterson et al. 1999)
• Velocity dispersion is measured from the line in the rms spectrum.– The rms spectrum
isolates the variable part of the lines.
– Constant components (like narrow lines) vanish in rms spectrum
Velocity Dispersion of the Broad Line Region and the Virial Mass
MBH = f v2 RBLR/G
f depends on structure and geometry of broad line region
(based on Korista et al. 1995)
MBH-: Comparison of Active and Quiescent Galaxies
• Reverberation masses appear to fall along the MBH - relation for quiescent galaxies
• The scatter is also similar: ≲ a factor of 3
Bulge velocity dispersion(Courtesy C. Onken)
Mass
AGNs
Gals
How Can Quasar MBH be Determined?
• Stellar kinematics
• Gas kinematics
• Reverberation mapping
(√)
(√)
√ √
Local Universe Higher-z
• Scaling relations √ √
Virial Mass Estimates MBH = f v2 RBLR/G
• Reverberation Mapping: RBLR=cτ, vBLR
Radius – Luminosity Relation: (Kaspi et al. (incl MV) 2005; Bentz,Peterson,
Pogge,MV,Onken 2006, ApJ, submitted)
• Scaling Relationships:
MBH FWHM2 L β
RBLR Lλ(5100Å)0.50
RBLR Lλ(1350Å)0.53
(see e.g. Vestergaard 2002)
Single-Epoch Mass Estimates - CIV
• 1 scatter = factor 2.3
(Vestergaard & Peterson 2006)
Mergs/s10
)1350(λL
km/s10
FWHM(CIV)105.4M
53.0
44λ
2
36
BH
Log [VP(CIV, single-epoch)/M]
Log
[ M
BH
(R
e ve r
b er a
tio n
)/ M
]
Scaling Relationships: (calibrated to 2004 Reverberation MBH)
• CIV:
1σ uncertainty: factor ~3.5
• Hβ:
Virial Mass Estimates: MBH=f v2 RBLR/G
Mergs/s10
)1350(λL
km/s10
FWHM(CIV)104.5M
0.53
44λ
2
36
BH
Mergs/s10
)5100(λL
km/s10
β) FWHM(H108.3M
0.50
44λ
2
36
BH
(see also Vestergaard 2002, and McLure & Jarvis 2002 for MgII)
( Vestergaard & Peterson 2006)
NGC 5548
Filled circles: 1989 data from IUE and ground-based telescopes.
Open circles: 1993 data from HST and IUE.
… Dotted line corresponds to virial relationship with M = 6 × 107 M.
Highest ionizationlines have smallestlags and largest Dopplerwidths.
Peterson and Wandel 1999
R (M/V) -1/2
Virial Relationships
(Peterson & Wandel 1999, 2000; Onken & Peterson 2002)
Emission lines:SiIV1400, CIV1549, HeII1640, CIII]1909, H4861, HeII4686
• All 4 testable AGNs comply:– NGC 7469: 1.2 107 M
– NGC 3783: 3.0 107 M
– NGC 5548: 6.7 107 M
– 3C 390.3: 2.9 108 M
• Scalings between lines: vFWHM
2(H) lag (H)
vFWHM2(CIV) lag (CIV)
• R-L relation extends to high-z and high luminosity quasars:– spectra similar (e.g., Dietrich et al 2002)
– luminosities are not extreme• R-L defined for 1042 – 1046 erg/s
(Vestergaard 2004)
(Dietrich et al 2002)
Radius – Luminosity Relation (Data from Kaspi et al. 2005)
Main goal: improve scalinglaws by reducing scatter
Improving the Scaling Relationships
Issues:• Host galaxy contamination
– HST imaging
• Accuracy of Single-epoch MBH estimates
– HST & ground-based study (HST archive project, PI: MV)
• Improved Masses and RBLR
– Improved monitoring of nearby sources
R-L relation scatter dominates scatter in mass scaling law
(Bentz, Peterson, Pogge, MV, Onken 2006)
Talk OutlineI. Black Hole Mass
a. Determinationsb. Distributions
II. Black Hole – Galaxy Connection
III. Black Hole Evolution
Masses of Distant Quasars
• Ceilings at MBH ≈ 1010 M LBOL < 1048
ergs/s
• MBH ≈ 109 M beyond space density drop at z ≈ 3
(H0=70 km/s/Mpc; ΩΛ = 0.7)(Vestergaard 2004)
Quasars
• Dramatic space density drop at z ≳3
• Very luminous AGNs were much more common in the past.
• The “quasar era” occurred when the Universe was 10-20% its current age.
(Peterson 1997)
Masses of Distant Quasars
• Ceilings at MBH ≈ 1010 M LBOL < 1048
ergs/s
• MBH ≈ 109 M beyond space density drop at z ≈ 3
(H0=70 km/s/Mpc; ΩΛ = 0.7)(Vestergaard et al. in prep)
Masses of Distant Quasars
• Ceilings at MBH ≈ 1010 M LBOL < 1048
ergs/s
• MBH ≈ 109 M beyond space density drop at z ≈ 3
(DR3 Qcat: Schneider et al. 2005)(DR3 Qcat: Schneider et al. 2005) (Vestergaard et al. in prep)
Using MgII line to Estimate Black Hole Mass
• Bridge 0.8 ≲ z ≲ 1.3 gap• Will use SDSS to
calibrate MgII scaling law• Complications:
– FeII contamination of line and continuum
(Vestergaard & Wilkes 2001)
Requires template fitting
Talk Outline
I. Black Hole Masses
II. Black Hole – Galaxy Connection
III. Black Hole Evolution
High Redshift Quasars and their Galaxies • UV, radio, X-ray properties similar at z > 3 (e.g., Constantin et al.
2002; Dietrich et al. 2002; Stern et al. 2000; Mathur et al. 2002)
• Black holes of distant quasars are very massive ~ (1-5)x 109 M
– Are their host galaxies also massive and old?
• Circumstantial evidence for intense star formation on galaxy scales associated with quasars at z 4:≳
– strong sub-mm/far-IR emission: ~108 M warm dust
– strong CO emission: ~1011 M of cold molecular gas (Ohta et al. 1996; Walter et al. 2003)
Dust and CO emission: large scale star formation rates 500 – 2000 M/yr (e.g., Omont et al. 2001, Carilli et al. 2001)
High Redshift Quasars and their Galaxies
• Some evidence for massive, old galaxies:
– z~2 quasar hosts have bulge luminosity consistent with old passively evolving stellar populations (Kukula et al. 2001)
– Low-z host galaxies are dominated by old (8-14Gyr) stellar populations (Nolan et al. 2001)
Quasar Host Galaxies at High Redshift• Conclusive test: mean age
and mass of stellar bulge
• Study of the most massive black holes at z ≳ 4– HST UV imaging: young stars
L(1500Å) → star formation rate
– HST Cy15 IR imaging: older stars
– Spitzer mid-IR: warm dust
– Sub-mm data: cooler dust
– CO imaging: cold molecular gas
• Goals: – Characterize stellar bulge:
mean age, mean mass, and star formation rate
– Determine MBH /MBulge
(Vestergaard 2004)
Redshift →
(Data from Bruzual & Charlot 2003)
Black Hole to Bulge Mass Ratio at High Redshift
(Peng et al. 2006, in prep)
Lensed Quasar Host Galaxy at Redshift 4.7
Original data PSF+Galaxy Model Galaxy residual
VLA CO (2-1) emission imagewith Einstein Ring (Carilli et al. 2003)
HST ACS UV image
Strong sub-mm source
Talk Outline
I. Black Hole Masses
II. Black Hole – Galaxy Connection
III. Black Hole Evolution
Black Hole Growth in the Early Universe
Theoretical model predictions:
• Accretion only– Radiatively efficient– Radiatively inefficient
• Merger activity
• Obscured growth
• A combination of the above?
(Steed & Weinberg 2003)
Predicted evolution of black hole mass functions for different growth scenarios
Preliminary Mass Functions of Active Supermassive Black Holes
• Different samples show relatively consistent mass functions (shape, slope, normalization)
(Vestergaard & Osmer, in prep.; Vestergaard, Fan, Osmer et al., in prep.)
• Goal: constrain BH growth (with Fan, Osmer,
Steeds, Shankar, Weinberg)
(H0=70 km/s/Mpc; ΩΛ = 0.7)
• BQS: 10 700 sq. deg; B16.16mag
• LBQS: 454 sq. deg; 16.0BJ18.85mag
• SDSS: 182 sq. deg; i* 20mag
• DR3: 5000 sq. deg.; i* >15, 19.1, 20.2
Preliminary Mass Functions of Active Supermassive Black Holes
• Different samples show relatively consistent mass functions (shape, slope)
(Vestergaard & Osmer, in prep.; Vestergaard, Fan, Osmer et al., in prep.)
• Goal: constrain BH growth (with Fan, Osmer,
Steeds, Shankar, Weinberg)
(H0=70 km/s/Mpc; ΩΛ = 0.7)
• BQS: 10 700 sq. deg; B16.16mag
• LBQS: 454 sq. deg; 16.0BJ18.85mag
• SDSS: 182 sq. deg; i* 20mag
• DR3: 5000 sq. deg.; i* >15, 19.1, 20.2
Preliminary Mass Functions of Active Supermassive Black Holes
• Different samples show relatively consistent mass functions (shape, slope)
(Vestergaard & Osmer, in prep.; Vestergaard, Fan, Osmer et al., in prep.)
• Goal: constrain BH growth (with Fan, Osmer,
Steeds, Shankar, Weinberg)
(H0=70 km/s/Mpc; ΩΛ = 0.7)
• BQS: 10 700 sq. deg; B16.16mag
• LBQS: 454 sq. deg; 16.0BJ18.85mag
• SDSS: 182 sq. deg; i* 20mag
• DR3: 5000 sq. deg.; i* >15, 19.1, 20.2
Preliminary Mass Functions of Active Supermassive Black Holes
• Locally mapped volume (R ≤ 100 Mpc):
MBH ≤ 3x109 M
• SDSS color-selected sample and DR3: (Fan et al. 2001, Schneider et al. 2005)
~9.5 quasars per Gpc3 with MBH ≥ 5x109 M
→ need ~25 times larger volume locally (R ≤ 290 Mpc)
(H0=70 km/s/Mpc; ΩΛ = 0.7)
Summary • >>> We can do physics with active galaxies and quasars <<<• MBH in Active Nuclei can be determined to within an accuracy:
– Low-z: ~factor of 3 (measured)– Higher z: ~factor of 4 (estimated!!)
• Black hole mass distributions:– <MBH> ≈ 109 M, even at 4 z 6≲ ≲– Maximum black hole mass at ~1010 M
• Black Hole Evolution and Galaxy Formation in Early Universe:– Ongoing study of galaxies at high redshift with the most
massive black holes (~1010 M)– MBH /MBulge ratio
– Mass functions of active black holes– Constrain growth of black holes and their galaxy bulges by
comparing these data with theoretical evolutionary models
The M – σ Relationship• Vittorini, Shankar, & Cavalier 2005, astro-ph/0508640 (BH
growth history from merger/feedback events; simulation)
• Robertson et al. 2005, astro-ph/0506038 (mergers simulation)
• Di Matteo, Springel, & Hernquist 2005, Nature, 433, 604 (merger induced BH growth and starformation; simulation)
• Springel, Di Matteo, & Hernquist 2005, MNRAS, 361, 776 (BH/star formation feedback; simulations)
• Miralda-Escude & Kollmeier 2005, ApJ 619, 30 (stellar capture)
• Sazonov et al. 2005, MNRAS 358, 168 (radiative BH feedback)
• King 2003, ApJ 596, L27 (supercritical accretion, outflows)
• Adams et al. 2003, ApJ 591, 125 (rotating BH collapse model)
• ….and many more…..
Secondary Mass Estimation MethodsVia MBH - *
bulge RelationMeasured *
bulge :
CaII 8498, 8542, 8662Å; z < 0.06
(Tremaine et al. 2002)(Ferrarese et al. 2001)
M 4.0
1 scatter ≈ 0.3 dex
M 4.72; MF00
AGNs
Secondary Mass Estimation MethodsVia MBH - *
bulge Relation
[OIII]5007 FWHM *bulge
(Nelson & Whittle 1996; Nelson 2000)
(Boroson 2003)
Tremaine slope
Radio-louds
1 scatter ≈ 0.7 dex
• Line asymmetries
• Outflows• Radio sources
• (Interacting systems)
Secondary Mass Estimation MethodsVia MBH - *
bulge Relation
Fundamental Plane: e, re *
bulge MBH
• Possibly significantly uncertain
- nuclear glare- bulge/disk decomposition (e.g., McLeod & Rieke 1995; Barth et al 2003)
-FP scatter (~0.6dex for RGs; e.g. Woo & Urry 2002)
- MBH - *bulge scatter
(Barth et al. 2003)
1 scatter = ? ( 0.7dex)
FundamentalPlane
log re
FP(,<e>)
Secondary Mass Estimation MethodsVia MBH - Lbulge Relation
(McLure & Dunlop 2001, 2002)
MR Lbulge
1 scatter ≈ 0.45 - 0.6 dex
• Nuclear glare
• Bulge/disk decomposition (e.g., McLeod & Rieke 1995; Barth et al 2003)
• Scaling relation scatter ?
MBH(dynamical)
MBH(scaling)
To first order quasar spectra look
similar at all redshifts
(Dietrich et al 2002)
Radius – Luminosity Relations
2HH
24
)H(
rn
L
cnr
QU
r L1/2
To first order, AGN spectra look the same
Same ionization
parameter Same density
[Kaspi et al (2000) data]
Radius-UV Luminosity Relationship for High-z Quasars
(Korista et al. 1997)
M = VFWHM2 RBLR/G
↑ ↑ ↓0.1109 M 4500km/s 33 lt-days
Ф RBLR-2 L
Log Ф Log n(H)
<L> ≈ 1047 ergs/s
Radius-UV Luminosity Relationship for High-z Quasars
(Dietrich et al. 2002)
M = VFWHM2 RBLR/G
Ф RBLR-2
Reverberation Mapping
• Kinematics and geometry of the broad-line region (BLR) can be tightly constrained by measuring the emission-line response to continuum variations.
• Can be done with
UV/optical lines.NGC 5548, the most closely monitored Seyfert 1 galaxy
Reverberation Mapping Results
• BLR sizes are measured from the cross-correlation time lags between continuum and emission-line variations.
• This gives the first moment of the transfer function.
NGC 5548, the most closely monitored Seyfert 1 galaxy
Continuum
Emission line
Reverberation Mapping Assumptions1 Continuum originates in a single central source.
– Continuum source (1013–14 cm) is much smaller than BLR (~1016 cm)
– Continuum source not necessarily isotropic
2 Light-travel time is most important time scale.• Cloud response instantaneous
rec = ( ne B)1 0.1 n101 hr
• BLR structure stable dyn = (R/VFWHM) 3 – 5 yrs
3 There is a simple, though not necessarily linear, relationship between the observed continuum and the ionizing continuum.
• In practice, programs have concentrated on solving the
velocity-independent (or 1-d) transfer equation:
The Transfer Equation
dtCtL )()()(
– Transfer function is line response to a -function outburst.
• It is most common to determine the cross-correlation
function and obtain the “lag”
dtt )(ACF)()(CCF
• Under these assumptions, the relationship between the
continuum and emission lines is:
Emission-linelight curve
“TransferFunction”
ContinuumLight Curve
dtCVtVL )(),(),(
The Transfer Equation• The aim of reverberation mapping is to solve for the
transfer function from the observables, the continuum
light curve C(t) and the emission-line light curve L(V,t).
• As noted earlier, currently we have been able to get
only the cross-correlation lag with any certainty.
Emission-linelight curve
“TransferFunction”
ContinuumLight Curve
dtCVtVL )(),(),(
dtt )(ACF)()(CCF
Reverberation Mapping Results• AGNs with lags for
multiple lines show that highest ionization emission lines respond most rapidly ionization stratification
• Combine lag with line width to get a “virial mass”.