Probing Modified Gravity with Integrated Sachs-Wolfe CMB and Galaxy
  Cross-correlations
  We use the cross-correlation power spectrum of the integrated Sachs-Wolfe
(ISW) effect in the cosmic microwave background (CMB) temperature anisotropy
and galaxy fluctuations to probe the physics of late-time cosmic acceleration.
For this purpose, we focus on three models of dark energy that belong to a
sub-class of Horndeski theories with the speed of gravity equivalent to that of
light: Galileon Ghost Condensate (GGC), Generalized Cubic Covariant Galileon
(GCCG), and K-mouflage. In the GGC and GCCG models, the existence of
cubic-order scalar self-interactions allows a possibility for realizing
negative ISW-galaxy cross-correlations, while the K-mouflage model predicts a
positive correlation similar to the LCDM model. In our analysis, we fix the
parameters of each model to their best-fit values derived from a baseline
likelihood analysis with observational data from CMB, baryon acoustic
oscillations, and supernovae type Ia. Then we fit those best-fit models to the
ISW-galaxy cross-correlation power spectrum extracted from a collection of
photometric redshift surveys. We find that both GGC and GCCG models degrade the
fit to the ISW-galaxy cross-correlation data compared to LCDM. This is
attributed to the fact that, for their best-fit values constrained from the
baseline likelihood, the cubic-order scalar self-interaction gives rise to
suppressed ISW tails relative to LCDM. The K-mouflage best-fit model is largely
degenerate with the LCDM best-fit model and has a positively correlated
ISW-galaxy power close to that of LCDM.
