Boson star superradiance with spinning effects and in time domain

TL;DR

This paper investigates superradiance phenomena in boson stars, analyzing how waves are amplified through energy and angular momentum transfer in both frequency and time domains, including effects of spin and confinement.

Contribution

It provides a comprehensive analysis of superradiance in boson stars using linear and nonlinear methods, highlighting the impact of spin and cavity confinement on amplification.

Findings

Superradiance occurs in both static and spinning boson stars.

Amplification factors are consistent across linear and nonlinear approaches.

Confinement enhances wave amplification within a cavity.

Abstract

Superradiance, the process by which waves are amplified through energy and angular momentum transfer, can also occur in horizonless objects like boson stars, due to both the real space and internal field space rotations. In this work, we study superradiance in the frequency and time domains for static and spinning boson stars, constructed within general relativity and with a self-interacting complex scalar field as a matter source. Using linear perturbation theory and three dimensional nonlinear simulations, we calculate amplification factors and analyze energy and angular momentum transfer in scattering processes, with results showing consistency between approaches. Wave scattering inside a cavity containing a boson star is also examined, demonstrating the effects of confinement on amplification.