Constraints on Modified Gravity from ACT and SPT

TL;DR

This paper uses recent CMB measurements from ACT and SPT, combined with WMAP9 data, to place constraints on f(R) modified gravity theories, finding upper limits on the theory's lengthscale parameter.

Contribution

It provides new, tighter observational bounds on f(R) gravity parameters using high-precision CMB data from ACT and SPT.

Findings

SPT data yields B_0 < 0.14 at 95% c.l.

ACT data yields B_0 < 0.86 at 95% c.l.

Constraints improve upon previous bounds.

Abstract

The Atacama Cosmology Telescope (ACT) and the South Pole Telescope (SPT) have recently provided new and precise measurements of the Cosmic Microwave Background anisotropy damping tail. This region of the CMB angular spectra, thanks to the angular distortions produced by gravitational lensing, can probe the growth of matter perturbations and provide a test for general relativity. Here we make use of the ACT and SPT power spectrum measurements (combined with the recent WMAP9 data) to constrain f(R) gravity theories. Adopting a parametrized approach, we obtain an upper limit on the lengthscale of the theory of B_0 < 0.86 at 95% c.l. from ACT, while we get a significantly stronger bound from SPT with B_0 < 0.14 at 95% c.l..