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Evolution of High-Redshift Quasars

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Dust and star formation in high-z quasar host galaxies ... How to assemble such mass BHs and their host galaxies in less than 1Gyr? ... – PowerPoint PPT presentation

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Title: Evolution of High-Redshift Quasars


1
Evolution of High-Redshift Quasars
  • Xiaohui Fan
  • University of Arizona
  • Castel Gandolfo, Oct 2005
  • CollaboratorsStrauss,Schneider,Richards,
    Hennawi,Gunn,Becker,White,Rix,Pentericci, Walter,
    Carilli,Cox,Bertoldi,Omont,Brandt,
    Vestergaard,Eisenstein, Cool, Jiang,
    Diamond-Stanic, et al.

2
The Highest Redshift Quasars Today
  • zgt4 gt1000 known
  • zgt5 gt60
  • zgt6 9
  • SDSS i-dropout Survey
  • By Spring 2005 6600 deg2 at zABlt20
  • Nineteen luminous quasars at zgt5.7
  • Complete sample for bright quasars at z6
  • 8000 deg, 25 quasars by 2006
  • Next work on faint sample at z6


3
(No Transcript)
4
Outline
  • Evolution of luminosity function
  • BH masses at high-z
  • High-z quasar clustering and environment
  • Evolution of quasar spectra and metallicity
  • Dust and star formation in high-z quasar host
    galaxies

5

46,420 Quasars from the SDSS Data Release Three
5
Ly? forest
3
Ly?
2
CIV
redshift
CIII
MgII
FeII
1
FeII
H?
OIII
0
wavelength
4000 A
9000 A
6
Evolution of quasar densities
Density of quasars
SFR of galaxies
Bouwens et al.
Exponential decline of quasar density at
high redshift, different from normal galaxies,
mostly luminosity dependent
Richards et al. 2005, Fan e al. 2005
7
Quasar Density at z6
  • From SDSS i-dropout survey
  • Density declines by a factor of 40 from between
    z2.5 and z6
  • Cosmological implication
  • MBH109-10 Msun
  • Mhalo 1012-13 Msun
  • rare, 5-6 sigma peaks at z6 (density of 1 per
    Gpc3)
  • Assembly of massive dark matter halo environment?
  • Assembly of supermassive BHs?

Fan et al. 2004
8
Simulating z6 Quasars
  • The largest halo in Millennium simulation (500
    Mpc cube) at z6.2
  • Virial mass 5x1012 M_sun
  • Stellar mass 5x1010 M_sun
  • SFR 300 M_sun/year
  • Resembles properties of SDSS quasars
  • Even the largest N-body simulation not big enough
    to produce one SDSS z6 quasar
  • Today 1.5 x 1015 M_sun cluster
  • Much massive halos existed at z6, but..
  • How to assemble such mass BHs and their host
    galaxies in less than 1Gyr??
  • The universe was 20 tedd old
  • Initial assembly from seed BH at zgtgt10
  • Little or no feedback to stop BH/galaxy growth

Dark matter
galaxy
z6.2
z0
Springel et al. 2005
9
Early Growth of Supermassive Black Holes
Formation timescale (assuming Eddington)
Vestergaard 2004
Dietrich and Hamann 2004
Lack of spectral evolution in high-redshift
quasars ? quasar BH estimate valid at high-z BH
mass estimate using emission line width to
approximate gravitational velocity, accurate to a
factor of 3 5 locally
  • Billion solar mass BH at z6 indicates very
    early
  • growth of BHs in the Universe

10
Evolution of X-ray AGN LF-- downsizing
Hasinger et al. 2005
  • At high-luminosity X-ray and optical traces the
    same population
  • How does optically-selected quasar population
    evolve at low-luminosity?

11
Evolution of the Shape of Quasar LF
Richards et al. 2005
12
Evolution of Quasar LF Shape
Richards, et al. Fan et al. 2005
  • High-z quasar LF different from low-z
  • Bright-end slope of QLF is a strong function of
    redshift
  • Transition at z3 (where quasar density peaks in
    the universe)
  • Different formation mechanism at low and high-z?

13
Probing the Evolution of Faint Quasar
  • 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
  • Reaches AGN luminosity at z2.5
  • Few hundred faint quasars at zgt3
  • 10 20 at z6

14
Evolution of faint quasars in SDSS Deep Survey
  • Sample reaches AGN luminosity at z3
  • Strong evolution in LF shape
  • Simple luminosity evolution clearly not a good
    description
  • break luminosity evolves
  • -- downsizing
  • faint end slope also evolve
  • -- steeper at high-z?

Jiang et al. in prep.
15
Downsizing of optical quasars
16
High-z QLF from SDSS Deep Stripe Survey
z 4.5
  • High-z quasar LF different from low-z
  • High-z LF much flatter
  • Implies that more luminous quasars grow early in
    the Universe
  • Similar to the early growth of massive galaxies??
  • Quasars are not major contributors to
    reionization at zgt6

(high-z)
(low-z)
Fan et al. 2005
17
Quasar Two-point Correlation Function from SDSS
at zlt2.5
Van den Berk et al. in preparation
18
Clustering of Quasars
  • What does quasar clustering tell us?
  • Bias factor of quasars ? average DM halo mass
  • Clustering provides the most effective probe to
    the statistical properties of quasar host DM
    properties at high-redshift
  • Another hint of quasars at zgt3 being somewhat
    different from low-z quasars?

Wyithe and Loeb 2004
Fan et al. in preparation
19
Environment of a z6.3 quasar
  • Deep VLT i-z-J imaging
  • 19 i-dropout candidates
  • in 38 sq. arcmin at zlt25.6
  • gt6 times higher than in
  • GOODS etc.
  • (also Stiavelle et al. 2005)

quasar
izJ composite (z_lim 26) Pentericci et al.
20

The Lack of Evolution in Quasar Intrinsic
Spectral Properties

Ly a
NV
Ly a forest
OI
SiIV
  • Rapid chemical enrichment in quasar vicinity
  • Quasar env has supersolar metallicity -- metal
    lines, CO, dust etc.
  • High-z quasars and their environments mature
    early on

21
Chemical Enrichment at zgtgt6?
  • Strong metal emission ? consistent with
    supersolar metallicity
  • NV emission ? multiple generation of star
    formation from enriched pops
  • Fe II emission ? type II SNe some could be Pop
    III?
  • Question can we generalize the conclusion drawn
    from regions around central BHs to the whole
    early Universe?

Fan et al. 2001
Barth et al. 2003
22
Early enrichment of quasars
  • Metallicity in BLR of z6 quasars 1 -- 10 solar
  • Nuclear synthesis model shows
  • Normal IMF is sufficient (given high SFR)
  • Type Ia is not critical in Fe production
  • Mostly Pop III under-produce N/C
  • normal stars existed at very high-z in quasar
    environment.

Top-heavy IMF
PopIII
Normal IMF
Venkatesan et al. 2004
23
Lack of evolution in X-ray
X-ray - optical slope
X-ray photon index
Strateva et al. Shemmer et al.
24
z6 Quasar SEDs from X-ray to radio
dust
  • Lack of evolution in UV, emission line and X-ray
    ? disk and emission line regions form in very
    short time scale
  • old quasars in a young universe
  • But how about dust? Timescale problem running
    out of time for AGB dust Spitzer

25
Mid-IR SEDs of z6 Quasars
Min. from dust sublimation
  • Overall shape shows little evolution
  • But obj-obj variation significant
  • z6.42 quasar stronger dust emission with higher
    T?

26
BH mass distribution
CIV
? Upper Limit?
LM
Fan et al. gt1000 quasars at zgt3
McLure et al. SDSS DR 1
How fast can the most massive high-z BH grow?
Will it be stopped by negative feedback?
27
BH Accretion Rate
zgt3
zlt3
28
Evolution of Quasar BH Mass Function
  • Lack of spectral evolution
  • Similar BLR structure
  • BH mass scaling relation at low-z still valid at
    high-z
  • Quasar mass function represents accretion
    history traced by luminous quasars
  • Not surprisingly, closely follows evolution of
    luminosity function
  • Flatter MF at high-z
  • Probing evolution of accretion rate?
  • At zgt2 MF shape similar and flat at high-mass
    end, but the shape different at low-z

Vestergaard et al.
29
Probing the Host Galaxy Assembly
? Dust torus
Spitzer
ALMA
  • Cool Dust in
  • host galaxy

30
Sub-mm and Radio Observationof High-z Quasars
  • Probing dust and star formation in the most
    massive high-z systems
  • Advantage
  • No host galaxy contamination
  • Negative K-correction for both continuum and line
    luminosity at high-z
  • Give direction measurement to
  • Star formation rate
  • Gas morphology
  • Gas kinematics

31
Sub-mm and Radio Observationof High-z Quasars
  • Using IRAM and SCUBA 30 of radio-quiet quasars
    at zgt4 detected at 1mm (observed frame) at 1mJy
    level
  • ? submm radiation in
  • radio-quiet quasars
  • come from thermal
  • dust with mass 108 Msun
  • If dust heating came from starburst
  • ? star formation rate of
  • 500 2000 Msun/year
  • ?Quasars are likely sites
  • of intensive star formation
  • FIR luminosity not correlated
  • with UV luminosity of quasar

Arp 220
Bertoldi et al. 2003
32
PSS J23221944 (z4.12)
  • CO Einstein ring
  • Modeled by star-forming disk with 2kpc radius
  • CO line-width 280km/s
  • BH Mass 109 solar
  • Star formation rate 900 solar mass/year
  • 15 detections of CO at zgt2 (5/6 known CO sources
    at zgt4 are quasars)

Carilli et al. 2003
33
  • Submm, CO and CII 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

Mailino et al. 2005
34
High-resolution CO Observation of z6.42 Quasar
VLA CO 32 map
  • 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
  • lt M-sigma prediction
  • BH formed before
  • complete galaxy assembly?
  • caution selection effect when
  • using luminous quasars

1 kpc
Walter et al. 2004
Channel Maps
?60 km/s?
35
High-z vs. Low-z Quasars
  • LF evolution
  • Strong evolution in total density
  • Downsizing of characteristic luminosity
  • At zgt3
  • Declining density
  • Flatter LF/MF
  • Stronger clustering
  • Are high-z and low-z quasars different?
  • Spectral evolution
  • Little or no evolution in continuum/emission line
    properties
  • Dust properties might have changed
  • High-metallicity requires presence of evolved
    stellar pop at high-z
  • How does this constrain host evolution?
  • BH/galaxy co-evolution
  • Billion solar-mass BH at the end of reionization
  • Strong star-formation associated with BH growth
  • Has M-sigma relation established at high-z?

36
Question
  • Should one be surprised about the existence of
    luminous, high-mass, high metallicity quasars at
    the end of reionization?
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