Download Document

The Highest-Redshift Quasars
and Early Growth of Supermassive Black Holes
Xiaohui Fan
University of Arizona
June 21, 2004
High-redshift Quasars, Black Holes
and Galaxy Formation
– Existence of SBHs at the
end of Dark Ages
– BH accretion History in the
Universe?
Resolved CO emission from z=6.42 quasar
– Relation of BH growth and
galaxy evolution?
– Quasar’s role in reionization?
Evolution of Quasar Density
Detection of Gunn-Peterson Trough
Exploring the Edge of the Universe
New z~7 galaxies
Courtesy of Arizona graduate students
The Highest Redshift Quasars Today
•
•
•
•
z>4: >900 known
z>5: >50
z>6: 8
SDSS i-dropout
Survey:
– By Spring 2004: 6000
deg2 at zAB<20
– Sixteen luminous
quasars at z>5.7
– Five in the last year
• 30 – 50 at z~6
expected in the whole
survey
Outline
• The first luminous quasars
– Evolution of faint quasars
– Role in reionization
• Quasar clustering at high-redshift
– Constraining host properties
• Lack of quasar spectral evolution
– Metallicity and Chemical Evolution
• Early Black Hole Growth
– Is there an upper limit on the BH mass?
• Probing the growth of host galaxies
– Dust, gas and star-formation
• Collaborators: Strauss,Schneider,Richards,Gunn,
Becker,White,Rix,Pentericci,Walter,Carilli,Cox,
Omont,Brandt,Vestergaard,Eisenstein,Cool,Jiang,
plus many SDSS collaborators
17,000 Quasars from the SDSS Data Release One
5
Ly a
3
CIV
redshift
2
CIII
MgII
1
OIII
Ha
0
4000 A
wavelength
9000 A
Evolution of Quasar Luminosity
Function
SFR of Normal Gal
Exponential decline of quasar
density at high redshift, different
from normal galaxies
Quasar Density at z~6
• Based on 6000 sq. deg of SDSS idropout survey:
– Density declines by a factor of
~40 from between z~2.5 and z~6
– It traces the emergence of the
earliest supermassive BHs in the
Universe
• Cosmological implication
– MBH~109-10 Msun
– Mhalo ~ 1013 Msun
– How to form such massive
galaxies and assemble such
massive BHs in less than 1Gyr??
• The rarest and most biased
systems at early times
• The initial assembly of the
system must start at z>>10
 co-formation and co-evolution of
the earliest SBH and galaxies
Fan et al. 2004
Evolution of LF shape
• At low-z:
– 2dF: LF is well fit by double power law with pure luminosity evolution
 downsizing of BH activities
• What about high-redshift?
– Does the shape of quasar LF evolve?
– Do X-ray and optically-selected samples trace the same population?
– Key: how does faint quasars at high-z evolve?
X-ray, low-luminosity
Optical, high-luminosity
SDSS2
• SDSS Southern Deep Spectroscopic Survey
– 270 deg along Fall Equator in the Southern Galactic
Cap
– Down to ~25 mag in SDSS bands with repeated
imaging
– Spectroscopic follow-up using 300-fiber Hectospec
spectrograph on 6.5-meter MMT
– Quasar and early-type galaxy survey with flux-limit
about 3 mag deeper than SDSS main survey
– Few hundred faint quasars at z>3: LF and clustering
– 10 – 20 at z~6
High-z QLF from Precursor Survey
• High-z quasar LF
different from low-z
– Different triggering
mechanism at low and
high-z?
– Constraint quasar
accretion efficiency?
• Combining with
COMBO-17 and
GOODS
– Break in LF at M ~ – 24?
– Constrain quasar
contribution to the
reionization
z ~ 4.5
(high-z)
(low-z)
Gunn-Peterson Troughs in the
Highest-redshift Quasars
• Strong, complete Lyα and Lyβ
absorption in the five highest
redshift quasars at z>6.1
– Neutral fraction of IGM
increases dramatially at z>6
– The end of reionization epoch
What Reionized the Universe?
• Based on SDSS quasar
luminosity function:
– UV photons from
luminous quasars and
AGNs are not the
major sources that
ionized the universe
– Consistent with limit
from X-ray stacking of
Lyman break galaxies in
the UDF
– Star-formation? Soft Xray from mini-quasars?
Clustering of Quasars
• What does quasar clustering tell us?
– Correlation function of quasars vs. of dark matter
– Bias factor of quasars  average DM halo mass
– Clustering probably provides the most effective
probe to the statistical properties of quasar host
galaxies at high-redshift
– Combining with quasar density  quasar lifetime
and duty cycle
Large Scale Distribution
of Quasars
SDSS
2dF
Quasar Two-point Correlation
Function from SDSS at z<2.5
Van den Berk et al. in preparation
Evolution of Quasar Clustering
Fan et al. in preparation
The Lack of Evolution in
Quasar Intrinsic Spectral Properties
Ly a
NV
Ly a forest
OI
SiIV
•
Rapid chemical enrichment in quasar vicinity
•
High-z quasars and their environments matures early on
Chemical Enrichment at z>>6?
•
•
•
•
Strong metal emission  consistent with supersolar metallicity
NV emission  multiple generation of star formation
Fe II emission  might be from metal-free Pop III
Question: what exactly can we learn from abundance analysis of these most
extreme environment in the early universe?
Barth et al. 2003
Fan et al. 2001
BH Mass Estimates at high-redshift
1.
Virial theorem: MBH = v 2 RBLR/G
2. Empirical Radius – Luminosity Relation allows
estimates of RBLR:
RBLR  Lλ(5100Å)0.7

MBH  FWHM2 L 0.7 accurate to a factor of 3 - 5
• z<0.7 : Hβ
• z= 0.7 – 3: MgII
• z>3: CIV
Lack of spectral evolution in high-redshift quasars 
virial theorem estimate valid at high-z
Early Growth of
Supermassive Black Holes
Formation timescale
(assuming Eddington)
Vestergaard 2004
Dietrich and Hamann 2004
• Billion solar mass BH indicates very early
growth of BHs in the Universe
BH mass distribution
CIV
 Upper Limit????
L~M
Fan et al. >1000 quasars at z>3
McLure et al. SDSS DR 1
There might be an upper envelop
of BH Mass at MBH ~ few x 1010 M_solar
BH Accretion Rate
z>3
z<3
Black Hole Mass Function?
• Is there a real upper limit
of BH mass?
• What’s the distribution of
BH accretion efficiency at
high-redshift?
• How does accretion
history trace host galaxy
assembly?
Vestergaard et al. 2004 in prep
Probing the Host Galaxy Assembly
 Dust torus
Spitzer
ALMA
Cool Dust in
host galaxy
Sub-mm and Radio Observation
of High-z Quasars
• Probing dust and star formation in the most massive high-z galaxy
• Using IRAM and SCUBA: ~40% of radio-quiet quasars at z>4
detected at 1mm (observed frame) at 1mJy level
• Combination of cm and submm
 submm radiation in
radio-quiet quasars
come from thermal
dust with mass ~ 108 Msun
• If dust heating came from starburst
 star forming rate of
500 – 2000 Msun/year
Quasars are likely sites
of intensive star formation
Bertoldi et al. 2003
Arp 220
Submm and CO detection
in the highest-redshift quasar:
• Dust mass: 108 – 109Msun
• H2 mass: 1010Msun
• Star formation rate: 103/yr
 co-formation of SBH and
young galaxies
High-resolution CO Observation
of z=6.42 Quasar
• Spatial Distribution
– Radius ~ 2 kpc
– Two peaks separated by 1.7 kpc
• Velocity Distribution
– CO line width of 280 km/s
– Dynamical mass within central 2 kpc: ~ 1010
M_sun
– Total bulge mass ~ 1011 M_sun
< M-sigma prediction
VLA CO 3—2 map
1 kpc
Walter et al. 2004 submitted
Channel Maps
• BH formed before
galaxy assembly?
 60 km/s 
Summary
• Quasar Luminosity Function
– Strong evolution from z~3 to 6
– Relatively flat LF at high-redshift
– UV photons from quasars not important to reionization
• Quasar clustering
– Clustering strength of flux-limited sample increases with redeshift
– High-redshift quasars are strongly biased  halo mas
• Lack of quasar spectral evolution
– Quasar environment matured very early, with rapid chemical enrichment
– Black hole mass estimates from virial theorem probably reliable
• Early Black Hole Growth
– 1010 M_sun BH existed at z>6
– Is there a real upper limit?
• Radio and sub-mm probes of host galaxies
– High-redshift quasars are sites of specticular star-formation: 1000 M_sun/yr
– First resolved z~6 host galaxy: BH growth before galaxy assembly?
What’s Next?
• Environment and host galaxies of z>5 quasars
– Spitzer + ALMA: gas physics, star formation and
kinematics
• The First Quasar?
– Assuming SDSS QLF and Eddington accretion, the first
1010 M_sun BH in the observable Universe at z=8.5 to
11.5
– Within reach of the next generation ground and spacebased IR surveys