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LBC Bootes Y band Survey: Searching for the first z~7 Quasars

LBC Bootes Y band Survey: Searching for the first z~7 Quasars. Xiaohui Fan University of Arizona. AZ: Fan , Bian, Cool, Eisenstein, Liebert, Jiang, Yang, Weiner, Zabludoff INAF: Maiolino , Fiore, Fontana, Giallongo, Pentericcii LBTB: Jester , Kurk, Rix, Walter

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LBC Bootes Y band Survey: Searching for the first z~7 Quasars

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  1. LBC Bootes Y band Survey:Searching for the first z~7 Quasars Xiaohui Fan University of Arizona AZ: Fan, Bian, Cool, Eisenstein, Liebert, Jiang, Yang, Weiner, Zabludoff INAF: Maiolino, Fiore, Fontana, Giallongo, Pentericcii LBTB: Jester, Kurk, Rix, Walter LBTO: Green, Kuhn, Thompson Background: 46,420 Quasars from the SDSS Data Release Three

  2. reionization Two Key Constraints: WMAP 3-yr: zreion=10+/-3 2. IGM transmission: zreion > 6 From Avi Loeb

  3. Quest to the Highest Redshift Quasars IR survey UKIDSS, VISTA, LBT SDSS • z>4: >1000 known • z>6: 20 • SDSS i-dropout Survey: • Completed in June 2006: • 7700 deg2, zAB < 20 • 30 luminous quasars at 5.71<z<6.42 • CFHT High-z Quasar Survey (CFHTQS, Willott et al. ) • Goal: 400 deg2, zAB<22.5 • 4 quasars at z>6 published (more to come) • New highest-z quasar at z=6.43 • SDSS Faint Quasar Survey (SFQS): • faint quasars in the deep SDSS stripe (Jiang, XF et al.), • 300 deg2, zAB < 22.5 • eight z~6 quasar at 20 < zAB < 22 • Goal: quasar LF APM CCD Radio

  4. From SDSS i-dropout survey Density declines by a factor of ~40 from between z~2.5 and z~6 Cosmological implication MBH~109-10 Msun Mhalo ~ 1012-13 Msun rare, 5-6 sigma peaks at z~6 (density of 1 per Gpc3) Assembly of supermassive BHs? The universe is only ~20 teddington old, requiring non-stop Eddington accretion of 100 Msun from z>>20 Is Eddington-limited accrection from stellar seeds still permitted, or are alternative accretion modes (super-Eddington, intermediate mass BH) needed? Negative feedback at high-z Steep LF? Needs to push to z~7! Quasar Density at z~6 Fan et al. 2006

  5. The Lack of Evolution in Quasar Emission Line Properties z~6 composite Ly a Low-z composite NV OI SiIV Ly a forest Fan 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.. • Needs to push to z~7

  6. Keck/ESI 30min exposure  Gunn-Peterson Trough in z=6.28 Quasar Keck/ESI 10 hour exposure  White et al. 2003

  7. Evolution of Lyman Absorptions at z=5-6 z = 0.15

  8. Optical depth evolution accelerated z<5.7:  ~ (1+z)4.5 z>5.7:  ~ (1+z)>11 > Order of magnitude increase in neutral fraction of the IGM  End of Reionization Dispersion of optical depth also increased Some line of sight have dark troughs as early as z~5.6 But detectable flux in ~50% case at z>6 Non-uniform reionization or non-uniform IGM at z~6 Accelerated Evolution at z>5.7 (1+z)11 (1+z)4.5 Fan et al. 2006

  9. Probing Reionization History Fan, Carilli & Keating 2006

  10. A LBT Survey for Quasars at the Reionization Epoch • Target: NOAO deep-wide survey Bootes field • 9 deg2 high latitude field • Excellent multiwavelength data: UV-optical-NIR-Spitzer • Missing critical U and Y bands • LBC Survey: • Uspec and Y band survey • Covers entire Bootes NOAO area • ~40 min exposure per pointing • Y~23, U~25 limiting magnitude • AZ/INAF/LBTB joint program: 6 nights in 2008A • Goals: • Discovery 1-3 quasars at z=6.5 - 7.5 • Probe faint-end slope of quasar LF at z~6-7 • Faint T/Y brown dwarfs • Y band data for evolution of z~1.5 red galaxies • U band data for large scale distribution of z~3 Lyman break galaxies

  11. Searching for the first z~7 Quasars

  12. Y-band Selection of z~7 Quasars • LBC Y band : • blue cutoff at 9600A • Reasonable QE at 15-20% • Thick CCD chip: little fringing • Currently the most efficient Y-band survey machine • Subaru will soon have more efficient Y-band

  13. Selection of z~7 quasars:Needle(s) in a Haystack • Main Contaminants: • L/T/Y dwarfs • red/dusty galaxies at z~1.2-1.5

  14. LBC Survey Layout

  15. Bootes Survey Progress • Data taken from Jan to June in INAF/AZ/LBTB runs • 22.3 hours of good data taken (55% of total planned) • Completed the first pass (20 min exposure over entire area); part of the second pass data taken • Median seeing 0.86” in Y • After co-add: 0.6 - 1.3” • Depth (after ~20 min exp) • 8-sigma limiting mag: ~22.3 • 5-sigma 50% completeness: ~22.9 • On average 0.3 mag shallower than expected • Combination of brighter sky and lower QE • Preliminary data reduction done • Some bright source test follow-up with MMT

  16. Seeing Statistics • Y-band • Median 0.86” • Range 0.6-1.3” • ~15% elongated • U-band • Median 1.3” • Many images bad • Poor guiding

  17. MMT Test Spectroscopic Follow-up Observations • May/June with MMT Red-Channel Spectrograph • Deep-depletion LBL CCD • Were only able to observe targets to Y<21.8 • Bad seeing/telescope performance • <1 quasars at z>6.5 expected • Observed ~10 red targets, among them 3 i-dropouts • Follow-up results • Recovered three known bright (Y<21.5) quasars at z=5.5 to 6.1 • Discovered two T dwarfs • No z>6.5 quasars yet…

  18. Discovery of a faint mid-T dwarf • Y~21.6, the second faintest field T-dwarf known? • Optical-NIR-Spitzer colors consistent with ~T5 • Measurable proper motion from faint NOAO I- band detection to LBC position • ~30 km/s velocity over 8 years

  19. Lessons and Next Step • LBC data quality good: Y band is competitive • Need to increase integration time • Target selection: • Spitzer data OR deep J data needed • Proper motion information useful • Proposed Fall Field • XMM-LSS field from CFHTLS • 10 deg2 of deep ugriz data • Also Spitzer Legacy field • Spring: • Spectroscopic follow-up of faint LBC Bootes candidates with LUCIFER

  20. Probing Reionization History JWST, ELT 21cm, GRB, ALMA Fan, Carilli, Keating 2006

  21. Probing Reionization Era(LBT in the JWST Era) • IGM evolution at z>7 • G-P at z>7 • Dark GRBs - fast response • First metals in the IGM • Ly  emitters at z>7 • Narrow-band imaging survey in NIR • Mapping reionization topology • Extremely Metal Poor Stars • Key capabilities • Wide-field deep survey • GLAO • OH suppression • High resolution IR spectroscopy

  22. GMT & LBT Comparison

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