Probing Polarization States of Primordial Gravitational Waves with Cosmic Microwave Background Anisotropies

Abstract

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 (ℓ ≤ 16) 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 |ε| ≳ 0.35(r/0.05)-0.6.

Department(s)

Physics

Keywords and Phrases

CMBR theory; Gravity waves/theory; Inflation

International Standard Serial Number (ISSN)

1475-7516

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2007 Institute of Physics - IOP Publishing, All rights reserved.

Publication Date

01 Sep 2007

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