Quasar Surveys -- From Sloan to SNAP Xiaohui Fan University of Arizona May 17, 2004
Jan 12, 2016
Quasar Surveys-- From Sloan to SNAP
Xiaohui Fan
University of Arizona
May 17, 2004
Quasars and Galaxy Formation
• The Study of Quasars Probes:– Accretion history of BHs in the Universe
– Relation of BH growth and galaxy evolution
– State of intergalactic medium
– History of reionization probing the end of cosmic dark ages
Quasar Surveys in the last decade
• 1996: Veron-Veron catalog– 8609 quasars– 2833 AGNs
• 2dF quasar survey (1997 – 2002)– 25,000 quasars at z<2.8
• SDSS quasar survey (1999 – 2005+)– Currently: >50,000 quasars– Goal: 100,000 quasars– z<6.5
• Next?– Fainter magnitude– Higher redshift
17,000 Quasars from the SDSS Data Release One
wavelength4000 A 9000 A
reds
hift
0
1
2
3
5Ly a
CIV
CIII
MgII
HaOIII
Evolution of Quasar Luminosity Function
Exponential decline of quasar density at high redshift, different from normal galaxies
SFR of Normal Gal
Evolution of LF shape
• At low-z: 2dF results show that LF is well fit by double power law with pure luminosity evolution
• At z~4: quasar luminosity function much FLATTER than LF at z~2
Clustering of Quasars
• What does quasar clustering tell us?– Bias factor of quasars average DM halo mass
– A biased large scale power spectrum at high-z
– 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
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 HighestRedshift Quasars Today
• z>4: ~700 known • z>5: ~30 • z>6: 7 • SDSS i-dropout
Survey:– By Spring 2004: 6000
deg2 at zAB<20
– Fourteen luminous quasars at z>5.7
• 20 – 40 at z~6 expected in the whole survey
SDSS DiscoveriesTotal Discoveries
Quasar Density at z~6
• Based on nine z>5.7 quasars:– Density declines by a factor of ~20 from
z~3– 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
• Using Eddington argument, 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
Quasars are boring…
NVOI SiIV
Ly a
Ly a forest
High-z quasars and their environments matures early on
The Lack of Evolution in Quasar Intrinsic Spectral Properties
Early Growth of Supermassive Black Holes
Vestergaard 2004 Dietrich and Hamann 2004
Billion solar mass BH indicates very early Growth of BHs in the Universe
Formation timescale (assuming Eddington)
Mass function for different redshifts
Black Hole Mass Function
Vestergaard et al. 2004 in prep
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
From Avi Loeb
reionization
Gunn-Peterson troughs confirmed by new z>6 quasars
Strong Evolution ofGunn-Peterson Optical Depth
Fan et al. 2003
Transition at z~6?
Constraining the Reionization Epoch
• Neutral hydrogen fraction– Volume-averaged HI fraction
increased by >100 from z~3 to z~6
– Mass-averaged HI fraction > 1%
• At z~6: – Last remaining neutral regions
are being ionized
– The universe is >1% neutral
– Marks the end of reionization epoch??
Fan et al. in prep
mass ave.
vol. ave
The end of dark ages
• CMB polarization shows: substantial ionization by z~17:
• Combining GP with CMB reionization history:– Reionization last from 20 to 6? (600 million
years) ?– Reionization is not a phase transition– Reionization seems to be more complicated by
the simplest theory
Quasar Survey in Space?
• Limitations of current generation quasar surveys:– Shallow: Only probing the most luminous quasars
majority of high-z quasars have not been detected!
• Evolution of faint quasars unknown
• Majority of UV background at high-z not detected yet
– Optical: Highest redshift limit is ~6.5
Quasar Survey in Space?
• Deep:– Sampling the entire quasar population
– Probing “normal” BHs in average galaxies
– Possible with LSST
• Infrared: Breaking the z=7 Barrier– Emergence of the first luminous quasars in the
Universe
– Probing the history of the cosmic reionization
• Key issue:– How effectively can quasar be selected
photometrically, without a large spectroscopic survey?
Quasar Photo-z?
• Lyman break technical efficient at z>3 • At low-z, strong emission line passing through pass-bands
causes bumps in the color-z relation– Esp. 3000A bump
Quasar Photo-z usingSDSS photometry
• Weinstein et al. 2004, Richards et al. 2004 show:– With good (sigma <0.05) photometry
– 86% photo-z correct to within 0.3
– 65% photo-z correct to within 0.1
– 95% of photometrically-selected quasars are real quasars confirmed by spectroscopy
X-ray vs. Optical LF
There is very little overlap…
• do faint quasars evolve differently from luminous
quasars?
Evolution of Quasar/AGN Density
X-ray, low-luminosity Optical, high-luminosity
Luminosity Function: AGNs and QSOs
Hao et al. 2004
z=0
Probing the end of dark ages
• Panoramic: – 7000 sq.deg, effective
selection down to 24.5
– z~3 quasars: 200 – 400 per sq. deg
– Hundreds of z~6 quasars
– Maybe 10 luminous quasars at z = 9 – 10?
Probing Reionization History
Double reionization model:• Early reionization at z>10• Second dark age at z<8.5
SNAP Spectrograph
Quasar Astrophysics
• Large scale structure host galaxy masses– Quasar clustering
– Quasar weak lensing
• Strong lensing• Variability revebretion mapping and BH mass• High resolution imaging of host galaxies
GEMS/COMBO-17: quasar host galaxies
Kormendy relation fromGEMS host galaxies
Wisotzki et al. 2004
Summary
• Current quasar survey shows– Strong evolution of luminous quasar number density– Strong clustering of luminous quasars– Existence of billion solar mass BHs at z~6– Emergence of Gunn-Peterson effect indicates the end of
reionization epoch by z~6
• A wide-field space-based quasar survey will– Probe the evolution of faint quasars and the evolution
of UV background at high-z– Reveal the evolution of first luminous quasars in the
Universe– Map the history of reionization at z = 6 – 10– Relation between quasar activity and galaxy formation
Courtesy of Arizona graduate students
SNAPS
SDSS: Structure Function
Structure function turnover
Strong Evolution ofGunn-Peterson Optical Depth
Fan et al. 2003
Transition at z~6?