Cosmology with variable parameters and effective equation of state for Dark Energy

TL;DR

This paper argues that a variable cosmological constant, possibly with a changing Newton's constant, can explain the evolving dark energy equation of state without requiring dynamical fields, challenging common assumptions.

Contribution

It demonstrates that a variable cosmological constant can naturally account for evolving dark energy properties without invoking dynamical scalar fields.

Findings

Variable cosmological constant can mimic evolving dark energy EOS

No need for dynamical fields to explain dark energy behavior

Potentially includes a variable Newton's constant

Abstract

A cosmological constant, Lambda, is the most natural candidate to explain the origin of the dark energy (DE) component in the Universe. However, due to experimental evidence that the equation of state (EOS) of the DE could be evolving with time/redshift (including the possibility that it might behave phantom-like near our time) has led theorists to emphasize that there might be a dynamical field (or some suitable combination of them) that could explain the behavior of the DE. While this is of course one possibility, here we show that there is no imperative need to invoke such dynamical fields and that a variable cosmological constant (including perhaps a variable Newton's constant too) may account in a natural way for all these features.