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Evolution of the

Evolution of the. Reionization @ Ringberg 25.03.2009. He-ionizing background. Keri Dixon University of California, Los Angeles Steven Furlanetto. Looking for the photoionization rate. Assume background ionization flux:. The attenuation length R 0 is treated as an unknown.

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Evolution of the

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  1. Evolution of the Reionization @ Ringberg 25.03.2009 He-ionizing background Keri Dixon University of California, Los Angeles Steven Furlanetto

  2. Looking for the photoionization rate Assume background ionization flux: The attenuation length R0 is treated as an unknown. When convenient, choose Bolton et al. 2006 The emissivity en is also uncertain.

  3. Begin with tHe II HE 2347-4342:Zheng et al. 2004, Shull et al. 2004, Kriss et al. 2001 HS 1700+64: Fechner et al. 2006, Davidsen et al. 1996 Q0302-003: Heap et al. 2000, Hogan et al. 1997 HS 1157+3143: Reimers et al. 2005 PKS 1935-692: Anderson et al. 1996

  4. From teff to G Start with the Gunn-Peterson optical depth Balance photoionization and recombination for HeII Introduce the fractional density of the IGM (D) with p(D) Miralda-Escudé et al. 2000 Assume isothermal equation of state

  5. Fluctuating vs. Uniform Helium reionization driven by quasarsfluctuating G Uniform ~ R0 = ∞ The attenuation length and ionized fraction affect distribution. Furlanetto 08

  6. Evolution of G Choose convenient R0 Pin to curve at z = 2.45 Significant departure from curve z ~ 2.75 (?) Uncertain (mainly) due to limited lines of sight

  7. Evolution of R0 Choose convenient G Pin to curve at z = 2.45 Significant jump z ~ 2.75 (?) Fluctuating background smoothes evolution

  8. What do we see? Choose convenient R0 Assume convenient G Find expected teff Data could distinguish the three regimes

  9. Where’s reionization?

  10. Time for lunch…just kidding It seems like probably something is happening around z ~ 2.75 Possible conclusions: Reionization is happening near this redshift This “something” does not indicate reionization The model is an insufficient approximation

  11. Including T-dependence

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