The Most Distant Quasars

Xiaohui Fan University of Arizona June 7, 2010

Collaborators: Brandt, Carilli, de Rosa,

Jiang

, Kurk, Richards, Schneider, Shen, Strauss, Vestergaard, Walter,

Wang

Background: 46,420 Quasars from the SDSS Data Release Three

Quasar of the day

• Last night’s astro-ph: Willott et al. new highest redshift quasar at z=6.44

Quest to the Highest Redshift

30 at z>6 60 at z>5.5

>100 at z>5

Key Questions

• • • When did the first supermassive BH form?

– Measurement of quasar luminosity function and BH mass at z>6 When did the first quasar form?

– (lack of ?) Evolution of spectral energy distribution Co-evolution of the earliest BHs and galaxies – Does M-σ relation exist at z>6?

Formation of z~6 quasars from hierarchical mergers

Li et al. 2007

Li et al. 2007

Theorists Tell us

• These luminous z~6 quasars: – The most massive system in early Universe – – – Living in the densest environment BH accreting at Eddington Host galaxies have ULIRG properties with maximum starburst

Quasar Evolution at z~6

• • • Strong density evolution – Density declines by a factor of ~40 from between z~2.5 and z~6 Black hole mass measurements – – –

M BH ~10 9-10

M halo ~ 10 12-13 rare, 5-6 sigma peaks at z~6 (density of 1 per Gpc 3)

M sun

M sun Luminosity function at z~6 – – Bright end slope steep LF breaks at M~-25 • Not likely significant contributor to reionization budget • bad news for deep quasar surveys

Low-z

Fan et al. 2006

z~6

Willott et al. 2010

Eddington Ratios in z~6 Quasars

z~6 quasars

• Quasar BH mass measured from near-IR spectroscopy in CIV and MgII regions •

On average: at or close to Eddington accretion

See De Rosa poster

Are there luminous quasars at z>>7

• • Black Holes do not grow arbitrarily fast – – – Accretion onto BHs dicitated by Eddington Limit E-folding time of

maximum

supermassive BH growth: 40 Myr At z=7: age of the universe: 800 Myr =

maximum

20 e-folding Billion solar mass BH at z>7 • Non-stop, maximum accretion from 100 solar mass BHs at z=15 (collapse of first stars in the Universe) •

Theoretically difficult for formation of z>7 billion solar mass BHs by Eddington-limited accretion from stellar seeds

• What if we find them: – – Direct collapse of “intermediate” mass BHs?

More efficient accretion model “super-Eddington”?

non-evolution of quasar (black hole) emission

z~6 composite Low-z composite Ly a NV Ly a forest OI SiIV • • • XF et al. 2010 Jiang, XF et al. 2008 Rapid chemical enrichment in quasar vicinity Quasar env has supersolar metallicity : no metallicity evolution High-z quasars are old, not yet first quasars, and live in metally enriched env

similar to centers of massive galaxies

When did the first quasar form?

Dust: emitting in infrared radiation from X-ray to radio as a result of black hole accretion and growth

Hot dust in z~6 Quasars

• • • • Lack of evolution in UV, emission line and X-ray  disk and emission line regions form in very short time scale But how about dust? Timescale problem: running out of time for AGB dust Spitzer observations of z~6 quasars: probing hot dust in dust torus (T~1000K) Three unusual SEDs among ~30 objects observed.

dust

No hot dust??

Jiang, XF et al. 2006, 2010

typical

Disappearance of Dust Torus at z~6?

J0005 3.5

 m 4.8

 m 5.6

 m 8.0

 m 16  m 24  m •

quasars with no hot dust

• Spitzer SEDs consistent • with disk continuum only

No similar objects known

•

at low-z no enough time to form hot dust tori? Or formed in metal-free environment?

Jiang, XF et al. 2010

Epoch of first quasars?

Dust-free quasars: • • Only at the highest redshift • With the smallest BH mass

First generation supermassive

•

BHs from metal-free environment?

How are they related to PopIII?

BH mass Jiang, XF et al. 2010

Probing quasar host galaxies at high-z

[OIII] Direct imaging: hard!

Radio/sub-mm

!

CO

Star Formation in z~6 Quasars

• • 30% of z~6 quasars detected at 1mJy level in 1-mm -> – – – L FIR ~ 10 13 L sun T~50K

SFR~1000 M sun yr -1

dust heated by SB) (if New CO observations – eight quasars detected in CO – Probing ISM properties and host galaxy masses Wang et al. 2008, 2009

1kpc Walter et al. 2004

Maximum starburst in z=6.4 quasar ?

• • Spatially resolved CO and [CII] emissions: – Size: ~1.5 kpc from [CII] (0.3”) – – Continuum has >50% extended component: SB heating?

Star formation rate of: ~1000 M sun yr -1 kpc -2 • Eddington limited maximum star formation rate (Thompson et al.)?

• Gas supply exhaused over a few t dyn – Similar SF intensity to Arp 200 but 100 times larger!

Dynamical mass: – – – – CO/CII line width ~300km/s Dynamical mass ~10 11 M sun?

BH formed earlier than completion of galaxy assembly?

Walter et al. 2009

•

Do z~6 Quasars Live in the Densest Environments?

High-redshift quasars are strongly clustered • Shen et al. 2007 But efforts to look for overdensity around z~6 quasars have mostly produced non-results (Willott et al., Kim et al., Kurk et al., Zheng et al.)

•

Do z~6 Quasars Live in the Densest Environments?

Non-detection of significant overdensity around z~6 quasars: – – – Quasars suppress dwarf galaxy formation?

Quasar hosts are not massive?

Needs deeper and wider surveys Overzier et al. 2008

Conclusions and Questions

• • • • Rapid evolution of quasar density at z~6 – Are we closing in to the epoch of the earliest SBH formation?

First hot dust at z~6 – Are we closing in to the epoch of first AGN structure?

Luminous quasars seem to live in modest environments – Narrow CO line width  small host mass – No significant overdensity of galaxies –

How closely tied are the earliest SBHs and galaxies? Or are we just picking up early starters in term of BH accretion in the most luminous quasars?

Important changes at z~6:

needs to push for higher redshift and lower luminosities

Quest to the Highest Redshift

Quest to the Highest Redshift

090423 080913 050904 000131 GRBs 970228

Probing Reionization History

WMAP