Excited Boson Stars

TL;DR

This paper investigates axisymmetric rotating radially excited boson stars, revealing their unique solution structure, energy properties, and stability, contrasting with nodeless boson stars and expanding understanding of scalar field configurations in gravitational systems.

Contribution

It provides the first detailed analysis of radially excited boson stars, showing their distinct loop-shaped solution behavior and stability characteristics.

Findings

Radially excited boson stars form loops in solution space, not spirals.

Two solutions exist for most boundary conditions, one trivial and one most compact.

Energy density and pressures are characterized, and stability is discussed.

Abstract

Axisymmetric rotating radially excited boson stars are analyzed. For several fixed parameter sets, the full sets of solutions are obtained. In contrast to the nodeless boson stars, the radially excited sets of solutions do not exhibit a spiraling behavior. Instead they form a loop, when the boson frequency is varied from its maximal value given by the boson mass to a minimal value and back. Thus for all allowed boundary data of the scalar field at the origin, there are two distinct solutions, except for the endpoints. While one endpoint corresponds to the trivial solution, the other one represents the most compact solution. The energy density and the pressures of the solutions are analyzed. A decomposition of the scalar field into spherical harmonics is performed, and stability considerations are presented.