Retrograde Polish Doughnuts around Boson Stars

TL;DR

This paper explores the structure and features of retrograde Polish doughnuts around rotating boson stars, revealing unique phenomena like static rings and static surfaces not found in Kerr black hole spacetimes.

Contribution

It introduces the classification of retrograde Polish doughnuts around boson stars and uncovers new features such as static rings and static surfaces.

Findings

Retrograde tori can have two centers connected by a cusp.

Boson stars feature static rings absent in Kerr black holes.

Static surfaces exist where fluid moves prograde inside static rings.

Abstract

We investigate Polish doughnuts with a uniform constant specific angular momentum distribution in the space-times of rotating boson stars. In such space-times thick tori can exhibit unique features not present in Kerr space-times. For instance, in the context of retrograde tori, they may possess two centers connected or not by a cusp. Rotating boson stars also feature a static ring, neither present in Kerr space-times. This static ring consists of static orbits, where particles are at rest with respect to a zero angular momentum observer at infinity. Here we show that the presence of a static ring allows for an associated static surface of a retrograde thick torus, where inside the static surface the fluid moves in prograde direction. We classify the retrograde Polish doughnuts and present several specific examples.