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Reionization science from the CMB after Planck

Reionization science from the CMB after Planck. Michael Mortonson. University of Chicago. July 2, 2009. Outline 1. Outline. Current reionization constraints and expected improvements from Planck and CMBPol (large-scale polarization) optical depth

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Reionization science from the CMB after Planck

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  1. Reionization science from the CMB after Planck Michael Mortonson University of Chicago July 2, 2009

  2. Outline 1 Outline • Current reionization constraints and expected improvements from Planck and CMBPol (large-scale polarization) • optical depth • physical parameters (reionization sources) • model-independent information • Separating reionization from other phenomena (e.g. inflation) Reionization report from June 2008 Fermilab CMBPol workshop: Zaldarriaga, Colombo, Komatsu, Lidz, Mortonson, Oh, Pierpaoli, Verde, & Zahn arXiv:0811.3918 Michael Mortonson U Chicago/KICP

  3. Reionization The End of Reionization Fan, Carilli, & Keating (2006) Michael Mortonson U Chicago/KICP

  4. Reionization peak Reionization from Large-Scale E-modes • Free electrons from reionization rescatter CMB photons • Local quadrupole generates polarization • Scattering at low redshifts projects onto large angular scales Michael Mortonson U Chicago/KICP

  5. Usual approach: inst. reion. WMAP Optical depth: t = 0.09 ± 0.02 Allowed effects of reionization at 6<z<30 Mortonson & Hu (2008) Michael Mortonson U Chicago/KICP

  6. Usual approach: inst. reion. Planck and CMBPol • Expect improved constraints on: • optical depth (time of reionization) • parameters of physical reionization models • general reionization histories Michael Mortonson U Chicago/KICP

  7. Usual approach: inst. reion. Optical Depth CMBPol WMAP: st = 0.017 Planck: st = 0.005 WMAP CMBPol: st = 0.0025 [Fermilab report] Michael Mortonson U Chicago/KICP

  8. Usual approach: inst. reion. Optical Depth Does the optical depth come from high z or low z? WMAP Planck CMBPol [Fermilab report] Michael Mortonson U Chicago/KICP

  9. Usual approach: inst. reion. Physical Models Simple model – assume that DM halos of mass M > Mmin host radiation sources that ionize regions of mass zM: WMAP Planck CMBPol [Fermilab report] Michael Mortonson U Chicago/KICP

  10. Usual approach: inst. reion. General Reionization Histories • Models of reionization may not capture all relevant physical processes • How much information about the general evolution of the ionization fraction can we get from large-scale CMB polarization (regardless of what it tells us about particular models)? Michael Mortonson U Chicago/KICP

  11. Usual approach: inst. reion. General Reionization Histories • Models of reionization may not capture all relevant physical processes • How much information about the general evolution of the ionization fraction can we get from large-scale CMB polarization (regardless of what it tells us about particular models)? CAMB/CosmoMC module for general reionization models: http://background.uchicago.edu/camb_rpc Michael Mortonson U Chicago/KICP

  12. Usual approach: inst. reion. General Reionization Histories Michael Mortonson U Chicago/KICP

  13. Usual approach: inst. reion. General Reionization Histories Michael Mortonson U Chicago/KICP

  14. Second parameter Reducing Reionization Confusion • Stronger constraints on reionization parameters will improve constraints on parameters degenerate with reionization • Example: inflationary features in CMB temperature and polarization Michael Mortonson U Chicago/KICP

  15. Second parameter Inflationary features and reionization Adams et al (2001), Covi et al. (2006) Michael Mortonson U Chicago/KICP

  16. Second parameter Inflationary features and reionization Planck: 2-3 s CMBPol: 5-6 s Mortonson, Dvorkin, Peiris, & Hu (2009) Michael Mortonson U Chicago/KICP

  17. Summary Summary • Future polarization data will improve constraints on reionization parameters – several times more precise than WMAP. • Can measure up to ~5 parameters describing the ionization history. • Precise determination of physical parameters or reconstruction of the ionization history will likely require additional information. • Potential confusion between effects of reionization and other large-scale polarization parameters can be greatly reduced. Michael Mortonson U Chicago/KICP

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