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Probing Reionization with z>6 Quasars

Probing Reionization with z>6 Quasars. Richard L. White Space Telescope Science Institute STScI Workshop, 2006 March 13. Collaborators. Rick White (STScI) Bob Becker (UCD/LLNL) Xiaohui Fan (Arizona) Michael Strauss (Princeton). … and the Sloan Digital Sky Survey Consortium.

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Probing Reionization with z>6 Quasars

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  1. Probing Reionizationwith z>6 Quasars Richard L. WhiteSpace Telescope Science Institute STScI Workshop, 2006 March 13

  2. Collaborators Rick White (STScI) Bob Becker (UCD/LLNL) Xiaohui Fan (Arizona) Michael Strauss (Princeton) … and the Sloan Digital Sky Survey Consortium

  3. Quasar composite spectra Flux Density f (Arbitrary Units) Vanden Berk et al. 2001, AJ, 122, 549 Rest Wavelength (Å)

  4. Red Blue Blue Red Quasar colors in SDSS filters Richards et al. 2001, AJ, 121, 2308

  5. Red Blue Quasar colors vs. redshift u - g g - r Richards et al. 2001, AJ, 121, 2308 i - z r - i

  6. The Lyman forest

  7. Selecting high-z quasars with SDSS + infrared Fan et al., 2003, AJ, 125, 1649

  8. Echelle Spectrograph & Imager Keck ESI raw spectrum

  9. 19 quasars with z>5.7 Fan et al., astro-ph/0512082

  10. And they’re still coming… • 5 new z > 6 quasars found at Keck since January 2006 • Including the first z>6 quasar found without SDSS:a FIRST radio-selected quasar at z=6.1 ~

  11. SDSS J1030+0524 z=6.31 White et al., 2003, AJ, 126, 1

  12. SDSS J1148+5251 z=6.42 White et al., 2003, AJ, 126, 1

  13. Gunn-Peterson troughs at z=6 White et al., 2003, AJ, 126, 1

  14. (Ly ) vs. redshift Fan et al., astro-ph/0512082

  15. (Ly ) vs. redshift Fan et al., astro-ph/0512082

  16. Evolution in photoionization rate Fan et al., astro-ph/0512082

  17. Line profiles at blue edge of Lyman  emission z>6.1 z=5.9–6.1 z=5.7–5.9 Fan et al., astro-ph/0512082

  18. H II region sizes around quasars • Size of ionized Strömgren sphere: • Increases with number of ionizing photons emitted in quasar’s lifetime • Decreases if IGM becomes more neutral • Decreases at higher redshift • Assumes recombinations are not important • rec ~ 5x107 yrs at z=6.4

  19. Observed H II region sizes around quasars • Conclusion: • Sizes decrease by factor of 2.7 from z = 5.7 to 6.4t = 1.4x108 yrs • Implies neutral fraction increases by factor of 14 Fan et al., astro-ph/0512082

  20. Summary of neutral hydrogen constraints from quasar spectra Fan et al., astro-ph/0512082

  21. Summary • Quasars are the most easily studied probes of the intergalactic medium at z > 6 • But only one bright z > 6 quasar per 500 square degrees • z = 6 probably marked the end of reionization • Neutral fraction still fairly low, fHI ~ 0.03 at z = 6.4 • Strongest limits: • Absorption in Ly  and Ly  Gunn-Peterson troughs • H II region sizes in proximity zone measured fromLy  line profiles

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