Recombination Corrections

 

The curve shown in Fig. 1 can be used to approximately account for the corrections to the recombination dynamics when analyzing future CMB data from the Planck Surveyor. The corresponding data-file can be downloaded here.


Details of the computation are explained in Chluba & Thomas, 2010, arXiv:1010.3631v1. All important corrections to the recombination dynamics, which have been discussed in the literature so far, are taken into account, including:


  1. •partial frequency redistribution by resonance and electron scattering

  2. •corrections to the 2s-1s two-photon channel

  3. •line feedback during Hydrogen and Helium recombination

  4. •two-photon transitions and Raman scatterings for the excited states

  5. •the HI continuum opacity during Helium recombination


To use the correction function in Fig. 1 for parameter estimation one simply has to multiply the output of Recfast (v1.4.2 with the helium switch set to zero) by f(z)=1+ΔNe/Ne. This procedure was explained in detail by Rubino-Martin et al., 2010, where it was also shown that neglecting the detailed recombination physics leads to biases in the cosmological parameters, most importantly ns and Ωbh2.

Fig. 1: Correction to the cosmological recombination history. We compared the output our detailed recombination code to Recfast v1.4.2, with the helium switch set to zero. The figure is taken from Chluba & Thomas, 2010, arXiv:1010.3631v1

If you use the above correction function please refer to:


  1. •Sunyaev & Chluba, 2009, AN, 330, 657

  2. •Rubino-Martin et al., 2010, MNRAS, 403, 439-452

  3. •Chluba & Thomas, 2010, arXiv:1010.3631


as well as:


  1. •Switzer & Hirata, 2008, Phys.Rev.D. 77, 083006

  2. •Grin & Hirata, 2010, Phys.Rev.D, 81, 083005

  3. •Ali-Haimoud & Hirata, 2010, Phys.Rev.D, 82, 063521