Degeneracy between nonadiabatic dark energy models and $\Lambda$CDM: ISW effect and the cross correlation of CMB with galaxy clustering data

Understand

As recently pointed out in Ref.

• [Phys.\ Rev.\ D {\bf 96}, 8, 083502 (2017)] the evolution of the linear matter perturbations in nonadiabatic dynamical dark energy models is almost indistinguishable (quasi-degenerated) to the standard $\Lambda$CDM scenario.
• In this work we extend this analysis to CMB observables in particular the integrated Sachs-Wolfe effect and its cross-correlation with large scale structure.
• We find that this feature persists for such CMB related observable reinforcing that new probes and analysis are necessary to reveal the nonadiabatic features in the dark energy sector.