Observational constraints on sign-changeable interaction models and alleviation of the H0 tension

Abstract

We investigate various scenarios which include interaction forms between dark matter and dark energy that exhibit sign reverse, namely where the transfer of energy between the dark fluids changes sign during evolution. We study the large-scale inhomogeneities in such interacting scenarios and we confront them with the latest astronomical data. Our analysis shows that the sign-changeable interaction models are able to produce stable perturbations. Additionally, the data seem to slightly favor a non-zero interaction, however, within 1σ confidence level (CL) the scenarios cannot be distinguished from non-interacting cosmologies. We find that the best-fit value of the dark-energy equation-of-state parameter lies in the phantom regime, while the quintessence region is also allowed nevertheless at more than 2σ CL. Examining the effect of the interaction on the CMB TT and matter power spectra we show that while from the simple spectra it is hard to distinguish the interacting case from ΛCDM scenario, in the residual graphs the interaction is indeed traceable. Moreover, we find that sign-changeable interaction models can reconcile the H0 tension, however the σ8 tension is still persisting. Finally, we examine the validity of the laws of thermodynamics and we show that the generalized second law is always satisfied, while the second derivative of the total entropy becomes negative at late times which implies that the universe tends towards thermodynamic equilibrium. 95.36.+x, 95.35.+d, 98.80.Es

Challenging bulk viscous unified scenarios with cosmological observations

“…We use weakly in the sense that the tension is released under 3σ CL. In summary, we see that the bulk viscous scenarios might be able to compete with other cosmological models in which an additional constraint in terms of either the inclusion of phantom dark energy equation of state [83,84,85,86,87] or the nonzero interaction [88,89,90,91,92], are necessary to release the H 0 tension.…”

All-inclusive interacting dark sector cosmologies

“…We refer to Refs. [27,31,34,40,41] for details concerning the linear perturbation theory within these coupled cosmologies.…”

CMB Tensions with Low-Redshift H0 and S8 Measurements: Impact of a Redshift-Dependent Type-Ia Supernovae Intrinsic Luminosity

“…Please note that the estimate of H 0 obtained with the inverse distance ladder technique [20], where a standard pre-recombination physics is assumed and BAO data are used, is also consistent with the value obtained with CMB data alone. Many studies have been dedicated to solve the tension between late-and early-time estimates of H 0 both from a theoretical [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] and observational [10,16,[40][41][42][43][44] point of view.…”