Numerical evidence for `multi-scalar stars'

TL;DR

This paper introduces a new class of gravitational solutions called phase-shifted boson stars, formed from multiple scalar fields, which are shown to be potentially stable and more common than previously believed.

Contribution

It presents a novel family of multi-scalar, soliton-like solutions in general relativity, expanding the understanding of scalar field configurations and their stability.

Findings

Phase-shifted boson stars are stable over long timescales.

These solutions are similar to known boson and oscillating soliton stars.

Scalar soliton-like solutions may be more prevalent than previously thought.

Abstract

We present a class of general relativistic soliton-like solutions composed of multiple minimally coupled, massive, real scalar fields which interact only through the gravitational field. We describe a two-parameter family of solutions we call ``phase-shifted boson stars'' (parameterized by central density rho_0 and phase delta), which are obtained by solving the ordinary differential equations associated with boson stars and then altering the phase between the real and imaginary parts of the field. These solutions are similar to boson stars as well as the oscillating soliton stars found by Seidel and Suen [E. Seidel and W.M. Suen, Phys. Rev. Lett. 66, 1659 (1991)]; in particular, long-time numerical evolutions suggest that phase-shifted boson stars are stable. Our results indicate that scalar soliton-like solutions are perhaps more generic than has been previously thought.