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The Most Distant Quasars

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.

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The Most Distant Quasars

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  1. 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

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

  3. Quest to the Highest Redshift

  4. 30 at z>6 60 at z>5.5 >100 at z>5

  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?

  6. Formation of z~6 quasars from hierarchical mergers Li et al. 2007

  7. 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 Li et al. 2007

  8. Strong density evolution Density declines by a factor of ~40 from between z~2.5 and z~6 Black hole mass measurements MBH~109-10 Msun Mhalo ~ 1012-13 Msun rare, 5-6 sigma peaks at z~6 (density of 1 per Gpc3) 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 Quasar Evolution at z~6 Fan et al. 2006 Low-z z~6 Willott et al. 2010

  9. Eddington Ratios in z~6 Quasars • Quasar BH mass measured from near-IR spectroscopy in CIV and MgII regions • On average: at or close to Eddington accretion z~6 quasars See De Rosa poster

  10. 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”?

  11. non-evolution of quasar (black hole) emission z~6 composite Ly a Low-z composite 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

  12. 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

  13. 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

  14. Disappearance of Dust Torus at z~6? typical 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

  15. 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? Dust/Bolometric Dust/Bolometric Jiang, XF et al. 2010 BH mass

  16. Probing quasar host galaxies at high-z [OIII] Direct imaging: hard! Radio/sub-mm! CO

  17. Star Formation in z~6 Quasars • 30% of z~6 quasars detected at 1mJy level in 1-mm -> • LFIR~ 1013Lsun • T~50K • SFR~1000 Msunyr-1 (if dust heated by SB) • New CO observations • eight quasars detected in CO • Probing ISM properties and host galaxy masses Wang et al. 2008, 2009

  18. 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 Msunyr-1kpc-2 • Eddington limited maximum star formation rate (Thompson et al.)? • Gas supply exhaused over a few tdyn • Similar SF intensity to Arp 200 but 100 times larger! • Dynamical mass: • CO/CII line width ~300km/s • Dynamical mass ~1011Msun? • BH formed earlier than completion of galaxy assembly? 1kpc Walter et al. 2004 Walter et al. 2009

  19. Do z~6 Quasars Live in the Densest Environments? • High-redshift quasars are strongly clustered • 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.) Shen et al. 2007

  20. 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

  21. 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

  22. Quest to the Highest Redshift

  23. Quest to the Highest Redshift 090423 080913 050904 000131 GRBs 970228

  24. Probing Reionization History WMAP

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