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?