The Atacama Cosmology Telescope: A Test of the Gravitational Force Law on Cosmological Scales Using the Kinematic Sunyaev-Zeldovich Effect

TL;DR

This study uses the kinematic Sunyaev-Zeldovich effect with data from the Atacama Cosmology Telescope and SDSS to test the gravitational force law on large cosmic scales, confirming it aligns with Newtonian predictions.

Contribution

First application of the kSZ effect to measure gravitational acceleration between galaxy halos over large scales, supporting standard cosmological gravity models.

Findings

Measured the gravitational acceleration exponent n=2.1±0.3, consistent with Newtonian gravity.

Confirmed inverse quadratic radial dependence of gravity over 30-230 Mpc scales.

Future surveys could definitively rule out alternative gravity models like n=1.

Abstract

The mean pairwise velocity of massive halos reflects the gravitational force law on cosmic scales. We combine cosmic microwave background intensity maps from the Atacama Cosmology Telescope and a galaxy catalog from the Sloan Digital Sky Survey to estimate the mean pairwise velocity using the kinematic Sunyaev-Zeldovich (kSZ) effect. On scales from 30 -- 230 megaparsecs, we constrain the gravitational acceleration between pairs of halos at separation $r$ to be $g\propto 1/r^n$ with $n=2.1\pm 0.3$, which is consistent with Newtonian gravity in an expanding spacetime (\textit{i.e.}, the standard $\Lambda$CDM model). This constraint shows agreement with an inverse quadratic radial dependence over the large distances separating galaxy halos, as expected in standard cosmology. Upcoming surveys have the potential to rule out $n = 1$ at $10\sigma$ significance. Our results establish the kSZ effect as a powerful tool for testing gravity on cosmological scales.