Linear kinetic Sunyaev-Zel'dovich effect and void models for acceleration

TL;DR

This paper investigates the use of the linear kinetic Sunyaev-Zel'dovich effect to test void models as an alternative explanation for cosmic acceleration, finding many such models are incompatible with observations.

Contribution

It provides a relativistic analysis of the kSZ effect on void models, highlighting theoretical and observational challenges and constraining the viability of these models.

Findings

Simplified models predict excessive kSZ power inconsistent with observations.

Relativistic treatment weakens the constraining power but still rules out many void models.

The combination of kSZ and other methods excludes a large class of void models.

Abstract

There has been considerable recent interest in cosmological models in which the current apparent acceleration is due to a very large local underdensity, or void, instead of some form of dark energy. Here we examine a new proposal to constrain such models using the linear kinetic Sunyaev-Zel'dovich (kSZ) effect due to structure within the void. The simplified "Hubble bubble" models previously studied appeared to predict far more kSZ power than is actually observed, independently of the details of the initial conditions and evolution of perturbations in such models. We show that the constraining power of the kSZ effect is considerably weakened (though still impressive) under a fully relativistic treatment of the problem, and point out several theoretical ambiguities and observational shortcomings which further qualify the results. Nevertheless, we conclude that a very large class of void models is ruled out by the combination of kSZ and other methods.