Circularly polarized scalar induced gravitational waves from the Chern-Simons modified gravity

Abstract We investigate the scalar induced gravitational waves (SIGWs) in the Chern-Simons (CS) modified gravity during the radiation dominated era. The SIGWs are circularly polarized, which provide us a tool to test the possible parity violation in the early universe. We derive the semianalytic exp...

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Bibliographic Details
Published inJournal of cosmology and astroparticle physics Vol. 2022; no. 10; pp. 54 - 74
Main Authors Zhang, Fengge, Feng, Jia-Xi, Gao, Xian
Format Journal Article
LanguageEnglish
Published Bristol IOP Publishing 01.10.2022
Subjects
Circular polarization
cosmological perturbation theory
Gravitational waves
gravitational waves / theory
modified gravity
Parity
Radiation
Relativity
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Summary:Abstract We investigate the scalar induced gravitational waves (SIGWs) in the Chern-Simons (CS) modified gravity during the radiation dominated era. The SIGWs are circularly polarized, which provide us a tool to test the possible parity violation in the early universe. We derive the semianalytic expressions to evaluate the fractional energy density of the SIGWs, Ω GW , which receives contributions from the general relativity (GR) and the correction due to the parity-violating term, respectively. We find that the degree of the circular polarization of the SIGWs can be as large as of order unity, although the contribution to Ω GW from the CS term is at most of the same order as that from the GR.
ISSN:1475-7516
1475-7516
DOI:10.1088/1475-7516/2022/10/054