Primordial Helium Abundance from CMB: a constraint from recent observations and a forecast

TL;DR

This paper constrains the primordial helium abundance using current CMB data and forecasts future constraints with Planck, analyzing how assumptions about Y_p influence other cosmological parameters.

Contribution

It provides the first constraint on Y_p from current CMB data and forecasts future constraints, exploring the impact of Y_p assumptions on cosmological parameters.

Findings

Current data yields Y_p = 0.25^{+0.10}_{-0.07} at 68% C.L.

Forecasts show Planck can significantly tighten Y_p constraints.

Assumptions about Y_p affect estimates of other cosmological parameters.

Abstract

We studied a constraint on the primordial helium abundance Y_p from current and future observations of CMB. Using the currently available data from WMAP, ACBAR, CBI and BOOMERANG, we obtained the constraint as Y_p = 0.25^{+0.10}_{-0.07} at 68% C.L. We also provide a forecast for the Planck experiment using the Markov chain Monte Carlo approach. In addition to forecasting the constraint on Y_p, we investigate how assumptions for Y_p affect constraints on the other cosmological parameters.