Spherically symmetric solutions in a FRW background

TL;DR

This paper derives new spherically symmetric solutions in a Friedmann-Robertson-Walker background, called Quasi Black Holes, analyzing their mathematical, physical, and thermodynamic properties.

Contribution

It introduces a novel class of solutions called Quasi Black Holes within a FRW background, expanding understanding of black hole-like objects in cosmological settings.

Findings

Identification of horizons and singularities in Quasi BHs

Analysis of thermodynamic properties of these solutions

Comparison with existing models like McVittie's solutions

Abstract

We impose perfect fluid concept along with slow expansion approximation to derive new solutions which, considering non-static spherically symmetric metrics, can be treated as Black Holes (BHs). We will refer to these solutions as Quasi BHs. Mathematical and physical features such as Killing vectors, singularities, and mass have been studied. Their horizons and thermodynamic properties have also been investigated. In addition, relationship with other related works (including McVittie's) are described.