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Ionized f(HI) ~ 0

Open Discussion 1 KIAA/PKU Reionization C. Carilli (facilitator), July 2008. Ionized f(HI) ~ 0. Neutral f(HI) ~ 1. Djorgovski + digital media center, CIT. Reionized f(HI) ~ 1e-5. Taking stock. Was the IGM substantially ionized (>50%) at z~20? Was the IGM partially neutral (>10%) at z~7?

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Ionized f(HI) ~ 0

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  1. Open Discussion 1 KIAA/PKU Reionization C. Carilli (facilitator), July 2008 Ionized f(HI) ~ 0 Neutral f(HI) ~ 1 Djorgovski + digital media center, CIT Reionized f(HI) ~ 1e-5

  2. Taking stock • Was the IGM substantially ionized (>50%) at z~20? • Was the IGM partially neutral (>10%) at z~7? • Was the Universe ionized by • Big galaxies • Small galaxies • Luminous quasars • Mini-quasars • Other • Is there any evidence for (massive) Pop III stars? • Is the MBH -- Mspheriod relation observationally unassailable, and if so, what is the physical origin? • Is GP effect simply a thickening of Lya forest (does it matter, physically)? • What is the largest bubble expected in 30o x 30o x (z=14 to 7)?

  3. Taking stock • Was the IGM substantially ionized (>50%) at z~20? (No - CMBpol) • Was the IGM partially neutral (>10%) at z~7? • Was the Universe ionized by • Big galaxies • Small galaxies • Luminous quasars (No, SDSS) • Mini-quasars • Other • Is there any evidence for (massive) Pop III stars? • Is the MBH -- Mspheriod relation observationally unassailable, and if so, what is the physical origin? • Is GP effect simply a thickening of Lya forest (does it matter, physically)? • What is the largest bubble expected in 30o x 30o x (z=14 to 7)?

  4. Constraint II: CMB large scale polarization -- Thomson scattering during reionization • Rules-out high ionization fraction at z> 15 • Allows for finite (~0.2) ionization to high z • Most action occurs at z ~ 8 to 14 • Is this evidence irrefutable (cf. Galacic FG), and is it relevant at z~7? ? Dunkley et al. 2008

  5. OI • Not ‘event’ but complex process, large variance: zreion ~ 6 to 14 • Good evidence for qualitative change in nature of IGM at z~6 ESO

  6. Integral measure? Geometry, pre-reionization? Local ionization? OI Abundance? Saturates, HI distribution function, pre-ionization? Local ioniz.? • Current probes are all fundamentally limited in diagnostic power • Need more direct probe of process of reionization = HI 21cm line

  7. Gunn-Peterson Effect toward z~6 SDSS QSOs Fan et al 2006 Is GP absorption fundamentally different than thickening of the Lya forest?

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