Collisional interactions between self-interacting non-relativistic boson stars: effective potential analysis and numerical simulations

TL;DR

This paper investigates the interactions and collisions of boson stars formed by light scalar particles, analyzing how parameters like self-interactions and phase differences influence their dynamics, with implications for dark matter models.

Contribution

It provides a detailed analysis of collisional interactions between boson stars, including effects of self-interactions and phase differences, using effective potential and numerical simulations.

Findings

Collision outcomes depend on mass ratios and phases.

Self-interactions significantly alter collision dynamics.

Results have implications for dark matter structure formation.

Abstract

Scalar particles are a common prediction of many beyond the Standard Model theories. If they are light and cold enough, there is a possibility they may form Bose-Einstein condensates, which will then become gravitationally bound. These boson stars are solitonic solutions to the Einstein-Klein-Gordon equations, but may be approximated in the non-relativistic regime with a coupled Schr\"odinger-Poisson system. General properties of single soliton states are derived, including the possibility of quartic self-interactions. Binary collisions between two solitons are then studied, and the effects of different mass ratios, relative phases, self-couplings, and separation distances are characterized, leading to an easy conceptual understanding of how these parameters affect the collision outcome in terms of conservation of energy. Applications to dark matter are discussed.