The Music of the Aetherwave - B-mode Polarization in Einstein-Aether Theory
Abstract
We study how the dynamical vector degree of freedom in modified gravity affects the CMB B-mode polarization in terms of the Einstein-aether theory. In this theory, vector perturbations can be generated from inflation, which can grow on superhorizon scales in the subsequent epochs and thereby leaves imprints on the CMB B-mode polarization. We derive the linear perturbation equations in a covariant formalism, and compute the CMB B-mode polarization using the CAMB code modified so as to incorporate the effect of the aether vector field. We find that the amplitude of the B-mode signal from the aether field can surpass the contribution from the inflationary gravitational waves for a viable range of model parameters. We also give an analytic argument explaining the shape of the spectrum based on the tight coupling approximation.
Keywords
Cite
@article{arxiv.1103.2197,
title = {The Music of the Aetherwave - B-mode Polarization in Einstein-Aether Theory},
author = {Masahiro Nakashima and Tsutomu Kobayashi},
journal= {arXiv preprint arXiv:1103.2197},
year = {2015}
}
Comments
12 pages, 6 figures