We review recent developments and results in testing general relativity (GR) at cosmological
scales. The subject has witnessed rapid growth during the last two decades with the aim of …

A stochastic background of gravitational waves could be created by the superposition of a
large number of independent sources. The physical processes occurring at the earliest …

We present the temperature and polarization angular power spectra of the CMB measured
by the Atacama Cosmology Telescope (ACT) from 5400 deg 2 of the 2013–2016 survey …

We present cosmological parameter results from the final full-mission Planck measurements
of the cosmic microwave background (CMB) anisotropies, combining information from the …

We present measurements of the cosmic microwave background (CMB) lensing potential
using the final Planck 2018 temperature and polarization data. Using polarization maps …

The Simons Observatory (SO) is a new cosmic microwave background experiment being
built on Cerro Toco in Chile, due to begin observations in the early 2020s. We describe the …

We review detection methods that are currently in use or have been proposed to search for a
stochastic background of gravitational radiation. We consider both Bayesian and frequentist …

Despite its continued observational successes, there is a persistent (and growing) interest in
extending cosmology beyond the standard model, Λ CDM. This is motivated by a range of …

We present the most significant measurement of the cosmic microwave background (CMB)
lensing potential to date (at a level of 40σ), using temperature and polarization data from the …

We report results from the BICEP2 experiment, a cosmic microwave background (CMB)
polarimeter specifically designed to search for the signal of inflationary gravitational waves …