English

Geometrically thick tori around compact objects with a quadrupole moment

General Relativity and Quantum Cosmology 2021-06-08 v1

Abstract

We study geometrically thick perfect-fluid tori with constant specific angular momentum, so-called "Polish doughnuts", orbiting deformed compact objects with a quadrupole moment. More specifically, we consider two different asymptotically flat, static and axisymmetric vacuum solutions to Einstein's field equation with a non-zero quadrupole moment, the q-metric and the Erez-Rosen spacetime. It is our main goal to find features of Polish doughnuts in these two spacetimes which qualitatively distinguish them from Polish doughnuts in the Schwarzschild spacetime. As a main result we find that, for both metrics, there is a range of positive (Geroch-Hansen) quadrupole moments which allows for the existence of double tori. If these double tori fill their Roche lobes completely, their meridional cross-section has the shape of a fish, with the body of the fish corresponding to the outer torus and the fish-tail corresponding to the inner torus. Such double tori do not exist in the Schwarzschild spacetime.

Cite

@article{arxiv.2103.04702,
  title  = {Geometrically thick tori around compact objects with a quadrupole moment},
  author = {Jan-Menno Memmen and Volker Perlick},
  journal= {arXiv preprint arXiv:2103.04702},
  year   = {2021}
}

Comments

28 pages, 12 figures

R2 v1 2026-06-23T23:52:22.371Z