Towards a complete treatment of the cosmological recombination problem
Abstract
A new approach to the cosmological recombination problem is presented, which completes our previous analysis on the effects of twophoton processes during the epoch of cosmological hydrogen recombination, accounting for ns1s and nd1s Raman events and twophoton transitions from levels with n≥ 2. The recombination problem for hydrogen is described using an effective 400shell multilevel approach to which we subsequently add all important recombination corrections discussed in the literature thus far. We explicitly solve the radiative transfer equation of the Lymanseries photon field to obtain the required modifications to the rate equations of the resolved levels. In agreement with earlier computations, we find that 2s1s Raman scattering leads to a delay in recombination by ∆N_{e}/N_{e}∼ 0.9 per cent at z∼ 920. Twophoton decay and the Raman scattering from higher levels (n > 3) result in small additional modifications, and precise results can be obtained when including their effect for the first three to five shells. This work is a major step towards a new cosmological recombination code (COSMOREC) that supersedes the physical model included in RECFAST, and which, owing to its short run time, can be used in the analysis of future cosmic microwave background data from the PLANCK Surveyor.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 April 2011
 DOI:
 10.1111/j.13652966.2010.17940.x
 arXiv:
 arXiv:1010.3631
 Bibcode:
 2011MNRAS.412..748C
 Keywords:

 cosmic background radiation;
 cosmological parameters;
 cosmology: observations;
 cosmology: theory;
 Astrophysics  Cosmology and Nongalactic Astrophysics;
 General Relativity and Quantum Cosmology;
 Physics  Atomic Physics;
 Quantum Physics
 EPrint:
 17 pages, 8 figures, minor typos corrected, accepted by MNRAS, CosmoRec available at http://www.Chluba.de/CosmoRec