Integrated Sachs-Wolfe effect in massive bigravity
  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.
