Sounds of instability from generalized QCD ghost dark energy

TL;DR

This paper analyzes the stability of the generalized QCD ghost dark energy model using sound speed criteria, finding it theoretically capable but observationally inconsistent with a stable universe.

Contribution

It provides a stability analysis of the generalized QCD ghost dark energy model considering interactions and geometry, highlighting observational constraints on its viability.

Findings

Model can be theoretically stable due to free parameter.

Observational constraints rule out stable universe scenario.

Stability results are consistent across different geometries and interaction cases.

Abstract

We investigate about the stability of generalized QCD ghost dark energy model against perturbations in the FRW background. For this purpose, we use the squared sound speed $v_s^2$ whose sign determines the stability of the model. We explore the stability of this model in the presence/absence of interaction between dark energy and dark matter in both flat and non-flat geometry. In all cases we find almost a same result. Based on the square sound speed analysis, due to the existence of a free parameter in this model, the model is theoretically capable to lead a dark energy dominated stable universe. However, observational constraints rule out such a chance. In conclusion, we find evidences that the generalized ghost dark energy might can not lead to a stable universe favored by observations at the present time.