On Black Ring with a Positive Cosmological Constant

TL;DR

This paper presents a new five-dimensional black ring solution with a positive cosmological constant in de Sitter supergravity, highlighting its unique properties and potential stability mechanisms despite singular horizons.

Contribution

It introduces a novel black ring solution in de Sitter space that preserves supersymmetry and explores its physical properties and stability conjectures.

Findings

The solution has horizons with S^1 x S^2 topology but is singular.

It carries a dipole charge affecting thermodynamics.

The solution's mass and entropy align with theoretical bounds.

Abstract

We consider black ring with a cosmological constant in the five dimensional N=4 de Sitter supergravity theory. Our solution preserves half of the de Sitter supersymmetries and has one rotation symmetry. Unlike the flat case, there is no angular momentum and the stability against gravitational self-attraction is balanced by the cosmological repulsion due to the cosmological constant. Our solution describes a singular black ring since although it has horizons of topology S^1 x S^2, the horizons are singular. Despite the singularity, our solution displays some interesting regular physical properties: it carries a dipole charge and this charge contributes to the first law of thermodynamics; it has an entropy and mass which conform to the entropic N-bound proposal and the maximal mass conjecture We conjecture that the Gregory-Laflamme instability leads to a resolution of the singularity and results in a regular black ring.