Revisiting Agegraphic Dark Energy in Brans-Dicke Cosmology

TL;DR

This paper investigates agegraphic dark energy models within Brans-Dicke cosmology, analyzing their evolution, stability, and ability to explain the universe's transition from deceleration to acceleration.

Contribution

It introduces sign-changeable interactions in ADE and NADE models in Brans-Dicke theory and examines their cosmological implications and stability.

Findings

Equation of state does not cross the phantom line.

Models can describe transition from deceleration to acceleration.

Both models lack stability signals for various parameters.

Abstract

We explore a spatially homogeneous and isotropic Friedmann-Robertson-Walker (FRW) universe which is filled with agegraphic dark energy (ADE) with mutual interaction with pressureless dark matter in the background of Brans-Dicke (BD) theory. We consider both original and new type of agegraphic dark energy (NADE) and further assume the sign of the interaction term can change during the history of the Universe. We obtain the equation of state parameter, the deceleration parameter and the evolutionary equation for the sign-changeable interacting ADE and NADE in BD theory. We find that, in both models, the equation of state parameter, $w_D$, cannot cross the phantom line, although they can predict the Universe evolution from the early deceleration phase to the late time acceleration, compatible with observations. We also investigate the sound stability of these models and find out that both models cannot show a signal of stability for different model parameters.