Parametrised modified gravity and the CMB Bispectrum

TL;DR

This paper explores how future measurements of the CMB bispectrum can significantly improve constraints on various modified gravity theories, which alter metric potential evolution and affect the bispectrum signal.

Contribution

It introduces a parametrised approach to forecast constraints on three classes of modified gravity models using the CMB bispectrum.

Findings

Future CMB bispectrum data will tighten constraints on modified gravity parameters.

Different classes of models show distinct signatures in the bispectrum.

Constraints on f(R) and Chameleon models improve notably with upcoming observations.

Abstract

We forecast the constraints on modified theories of gravity from the cosmic microwave background (CMB) anisotropies bispectrum that arises from correlations between lensing and the Integrated Sachs-Wolfe effect. In models of modified gravity the evolution of the metric potentials is generally altered and the contribution to the CMB bispectrum signal can differ significantly from the one expected in the standard cosmological model.We adopt a parametrised approach and focus on three different classes of models: Linder's growth index, Chameleon-type models and f(R) theories. We show that the constraints on the parameters of the models will significantly improve with future CMB bispectrum measurements.