2007/05/31 by Shun Saito, Kiyotomo Ichiki, Atsushi Taruya · 3 citations
Earth and Planetary Sciences · Physics and Astronomy · #Amplitude #Anisotropy #Astronomy #Astrophysics #Asymmetry #Black Holes and Theoretical Physics #CMB cold spot #Cosmic background radiation #Cosmic microwave background #Cosmology and Gravitation Theories #Galaxy #Geophysics and Gravity Measurements #Gravitational wave #Gravitational wave background #Inflation (cosmology) #Particle physics #Physics #Planck #Polarization (electrochemistry) #Quantum mechanics #Redshift #Reionization #astro-ph
paper · pdf · doi:10.1088/1475-7516/2007/09/002
published as JCAP 0709:002,2007 · 28 pages, 9 figures, Accepted for publication in JCAP
arxiv created 2007/08/08 · openalex publication_date 2007/09/03 · arxiv updated 2009/12/01 · openalex created_date 2019/06/27 · openalex updated_date 2026/08/06
We discuss the polarization signature of primordial gravitational waves imprinted in cosmic microwave background (CMB) anisotropies. The high-energy physics motivated by superstring theory or M-theory generically yields parity violating terms, which may produce a circularly polarized gravitational wave background (GWB) during inflation. In contrast to the standard prediction of inflation with unpolarized GWB, circularly polarized GWB generates non-vanishing TB- and EB-mode power spectra of CMB anisotropies. We evaluate the TB- and EB-mode power spectra taking into account the secondary anisotropies induced by the reionization and investigate the dependence of cosmological parameters. We then discuss current constraints on the circularly polarized GWB from large angular scales ( ) of the three year WMAP data. Prospects for future CMB experiments are also investigated based on a Monte Carlo analysis of parameter estimation, showing that the circular polarization degree, ε, which is the asymmetry of the tensor power spectra between right- and left-handed modes normalized by the total amplitude, can be measured down to .