Bifurcations in Bosonic Stars: chains and rings from spherical solutions

TL;DR

This paper investigates how spherical bosonic stars bifurcate into axisymmetric configurations like chains and rings under specific perturbations, revealing new star types and constructing multi-constituent chains and rings.

Contribution

It introduces a detailed numerical analysis of bifurcation phenomena in bosonic stars, identifying new axisymmetric star configurations and constructing multi-constituent chains and rings.

Findings

Excited spherical bosonic stars bifurcate into chain and ring configurations.

New gyroscope-like axisymmetric bosonic stars are identified.

Constructed chains of scalar bosonic stars with 7 constituents.

Abstract

We study the bifurcation phenomena between spherical and axisymmetric bosonic stars. By numerically solving for the zero-modes of spherical bosonic stars under specific axially symmetric perturbations, we discover that excited state spherical bosonic stars bifurcate into two types of axisymmetric bosonic stars under $\ell=2$ perturbations, with matter distributions resembling chains and rings, respectively. Meanwhile, $\ell=4$ axisymmetric perturbations lead spherical scalar bosonic stars to bifurcate into a new type of axisymmetric bosonic stars, exhibiting a mixed chain-like and ring-like matter distribution, which we refer to as gyroscope-like. Additionally, for the first time, we have constructed chains of scalar bosonic stars with 7 constituents and their corresponding ring-like scalar bosonic stars. Our results provide an explanation for the bifurcations in bosonic stars from the perspective of perturbations, and by analyzing physical quantities such as quadrupoles and energy densities we systematically discuss the impact of axisymmetric perturbations on spherical bosonic stars.