Large-Scale Structure and Gravitational Waves III: Tidal Effects

Fabian Schmidt; Enrico Pajer; Matias Zaldarriaga

doi:10.1103/PhysRevD.89.083507

paper

Large-Scale Structure and Gravitational Waves III: Tidal Effects

arXiv:1312.5616 · doi:10.1103/PhysRevD.89.083507

Abstract

The leading locally observable effect of a long-wavelength metric perturbation corresponds to a tidal field. We derive the tidal field induced by scalar, vector, and tensor perturbations, and use second order perturbation theory to calculate the effect on the locally measured small-scale density fluctuations. For sub-horizon scalar perturbations, we recover the standard perturbation theory result ( $F_{2}$ kernel). For tensor modes of wavenumber $k_{L}$ , we find that effects persist for $k_{L} τ ≫ 1$ , i.e. even long after the gravitational wave has entered the horizon and redshifted away, i.e. it is a "fossil" effect. We then use these results, combined with the "ruler perturbations" of arXiv:1204.3625, to predict the observed distortion of the small-scale matter correlation function induced by a long-wavelength tensor mode. We also estimate the observed signal in the B mode of the cosmic shear from a gravitational wave background, including both tidal (intrinsic alignment) and projection (lensing) effects. The non-vanishing tidal effect in the $k_{L} τ ≫ 1$ limit significantly increases the intrinsic alignment contribution to shear B modes, especially at low redshifts $z ≲ 2$ .

24 pages, 4 figures; v2: added references and corrected typos; v3: corrected factor of 2 in Sec. VI and intrinsic alignment matching, conclusions unchanged

Large-Scale Structure and Gravitational Waves III: Tidal Effects

Abstract

References in corpus (5)

Cited by in corpus (64)