# Presentation: 233786

## 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

## Outline

- Main Results from SDSS and 2dF surveys
- Evolution of Quasar Luminosity Function
- Quasar Clustering
- Early Growth of Supermassive Black Holes
- Constraints on the Reionization Epoch
- Expectation of Future Wide-field Space Surveys
- Photometric redshift estimates for quasars
- Evolution of faint quasars at high-redshift
- Prospects of finding quasars at z = 6 – 10

- 17,000 Quasars from the SDSS Data Release One

- wavelength

***4000 A***

***9000 A***

- redshift

***0***

***1***

***2***

***3***

***5***

- Ly a

- CIV

- CIII

- MgII

- Ha

- OIII

## 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

## Large Scale Distributionof Quasars

- 2dF

- SDSS

## 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 HighestRedshift 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 Discoveries

- Total Discoveries

## Slide 13

## 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...

- NV

- OI

- 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)

## Black Hole Mass Function

- Mass function for different redshifts

- Vestergaard et al. 2004 in prep

## 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

- Fan et al. 2001

- Barth et al. 2003

***Submm and CO detection          ***
***in the highest-redshift quasar***:
- 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 ofGunn-Peterson Optical Depth

- 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 usingSDSS 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

## Photo-z selected quasar number counts

## 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 from***
***GEMS 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 ofGunn-Peterson Optical Depth

- Strong Evolution ofGunn-Peterson Optical Depth

- Fan et al. 2003

***Transition at z~6?***