Dynamical evolution of fermion-boson stars

TL;DR

This paper investigates the stability and oscillation modes of fermion-boson stars, which are compact objects with dark matter components, revealing new modes due to the coupling of fermionic and bosonic matter.

Contribution

The study provides a dynamical evolution analysis of fermion-boson stars, identifying their stability structure and discovering new oscillation modes from fermion-boson coupling.

Findings

Fermion-boson stars exhibit stability patterns similar to isolated stars.

New oscillation modes are found in the fermionic component due to gravitational coupling.

Stable and unstable equilibrium configurations are identified.

Abstract

Compact objects, like neutron stars and white dwarfs, may accrete dark matter, and then be sensitive probes of its presence. These compact stars with a dark matter component can be modeled by a perfect fluid minimally coupled to a complex scalar field (representing a bosonic dark matter component), resulting in objects known as fermion-boson stars. We have performed the dynamical evolution of these stars in order to analyze their stability, and to study their spectrum of normal modes, which may reveal the amount of dark matter in the system. Their stability analysis shows a structure similar to that of an isolated (fermion or boson) star, with equilibrium configurations either laying on the stable or on the unstable branch. The analysis of the spectrum of normal modes indicates the presence of new oscillation modes in the fermionic part of the star, which result from the coupling to the bosonic component through the gravity.