Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1853431 | Physics Letters B | 2009 | 4 Pages |
Abstract
We discuss a method to constrain the fraction density f of the relativistic gas in the radiation-dominant stage, by their impacts on a relic gravitational waves and the cosmic microwave background (CMB) B-polarization power spectrum. We find that the uncertainty of f strongly depends on the noise power spectra of the CMB experiments and the amplitude of the gravitational waves. Taking into account of the CMBPol instrumental noises, an uncertainty Îf=0.046 is obtained for the model with tensor-to-scalar ratio r=0.1. For an ideal experiment with only the reduced cosmic lensing as the contamination of B-polarization, Îf=0.008 is obtained for the model with r=0.1. So the precise observation of the CMB B-polarization provides a great opportunity to study the relativistic components in the early Universe.
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Nuclear and High Energy Physics
Authors
Wen Zhao, Yang Zhang, Tianyang Xia,