Doubly-boosted vector cosmologies from disformal metrics

TL;DR

This paper uses a dynamical system approach to explore anisotropic Bianchi I cosmologies with vector fields in disformal metrics, identifying new fixed points and analyzing their stability and observational viability.

Contribution

It introduces a systematic dynamical system analysis of vector cosmologies with disformal metrics, revealing new fixed points and their stability properties.

Findings

Discovery of new anisotropic scaling solutions.

Most solutions are not stable or compatible with acceleration.

Some solutions maintain isotropy through rapid vector oscillations.

Abstract

A systematic dynamical system approach is applied to study the cosmology of anisotropic Bianchi I universes in which a vector field is assumed to operate on a disformal frame. This study yields a number of new fixed points, among which anisotropic scaling solutions. Within the simplifying assumption of (nearly) constant-slope potentials these are either not stable attractors, do not describe accelerating expansion or else they feature too large anisotropies to be compatible with observations. Nonetheless, some solutions do have an appeal for cosmological applications in that isotropy is retained due to rapid oscillations of the vector field.