Cosmological constraints on Λ(t)CDM models

Abstract

Problems with the concordance cosmology Λ$$\Lambda $$CDM as the cosmological constant problem, coincidence problems and Hubble tension has led to many proposed alternatives, as the Λ(t)$$\Lambda (t)$$CDM, where the now called Λ$$\Lambda $$ cosmological term is allowed to vary due to an interaction with pressureless matter. Here, we analyze one class of these proposals, namely, Λ=α′a-2+βH2+λ∗$$\Lambda =\alpha 'a^{-2}+\beta H^2+\lambda _*$$, based on dimensional arguments. Using SNe Ia, cosmic chronometers data plus constraints on H0$$H_0$$ from SH0ES and Planck satellite, we constrain the free parameters of this class of models. By using the Planck prior over H0$$H_0$$, we conclude that the λ∗$$\lambda _*$$ term can not be discarded by this analysis, thereby disfavouring models only with the time-variable terms. The SH0ES prior over H0$$H_0$$ has an weak evidence in this direction. The subclasses of models with α′=0$$\alpha '=0$$ and with β=0$$\beta =0$$ can not be discarded by this analysis. Finally, by using distance priors from CMB, the Λ$$\Lambda $$ time-dependence was quite restricted.