Data-constrained reionization and its effects on cosmological parameters
  We perform an analysis of the recent WMAP7 data considering physically
motivated and viable reionization scenarios with the aim of assessing their
effects on cosmological parameter determinations. The main novelties are: (i)
the combination of CMB data with astrophysical results from quasar absorption
line experiments; (ii) the joint variation of both the cosmological and
astrophysical [governing the evolution of the free electron fraction x_e(z)]
parameters. Including a realistic, data-constrained reionization history in the
analysis induces appreciable changes in the cosmological parameter values
deduced through a standard WMAP7 analysis. Particularly noteworthy are the
variations in Omega_bh^2 = 0.02258^{+0.00057}_{-0.00056} (WMAP7) vs.
Omega_bh^2$ = 0.02183\pm 0.00054 (WMAP7 + ASTRO), and the new constraints for
the scalar spectral index, for which WMAP7 + ASTRO excludes the
Harrison-Zel'dovich value n_s=1 at more than 3\sigma. Finally, the e.s. optical
depth value is considerably decreased with respect to the standard WMAP7, i.e.
\tau_{e}=0.080\pm 0.012. We conclude that the inclusion of astrophysical
datasets, allowing to robustly constrain the reionization history, in the
extraction procedure of cosmological parameters leads to relatively important
differences in the final determination of their values.
