Integrated Sachs-Wolfe effect in massive bigravity

TL;DR

This paper investigates the integrated Sachs-Wolfe effect within a specific massive bigravity model, comparing theoretical predictions with observational data to assess its viability as an alternative to dark energy.

Contribution

It introduces the infinite-branch bigravity model's predictions for the ISW effect and compares them with observational data, highlighting differences from the standard cosmological model.

Findings

ISW amplitudes are about 1.5 times larger than in LCDM.

Predicted ISW signals are consistent with WMAP and WISE data.

The model provides a viable alternative explanation for cosmic acceleration.

Abstract

We study the integrated Sachs-Wolfe (ISW) effect in ghost-free, massive bigravity. We focus on the infinite-branch bigravity (IBB) model which exhibits viable cosmic expansion histories and stable linear perturbations, while the cosmological constant is set to zero and the late-time accelerated expansion of the Universe is due solely to the gravitational interaction terms. The ISW contribution to the CMB auto-correlation power spectrum is predicted, as well as the cross-correlation between the CMB temperature anisotropies and large-scale structure. We use ISW amplitudes as observed by the WMAP 9-year temperature data together with galaxy and AGN data provided by the WISE mission in order to compare the theoretical predictions to the observations. The ISW amplitudes in IBB are found to be larger than the corresponding ones in the standard LCDM model by roughly a factor of 1.5, but are still consistent with the observations.