A survey of ultra-compact rotating boson star spacetimes

Abstract

Solitonic boson stars (SBS) are compact shell-like objects with an inside having a nearly constant value of scalar field bounded by a thin shell where the scalar field rapidly changes. While the spherically symmetric SBS can be described by an analytical approximation that works well in the thin-shell case, no such approximation exists for rotating SBS and the investigation of such stars poses a numerical challenge. We numerically investigate rotating SBS in case if the relative thickness of the shell is small. We compute Gerosh-Hansen multipole moments to study the structure of SBS spacetime in the outside region and the closeness of SBS to the rotating black hole metric.