Mass of perfect fluid black shells

TL;DR

This paper investigates the properties and observable masses of spherically symmetric perfect fluid shells at the event horizon, analyzing how their characteristics depend on physical parameters and equations of state.

Contribution

It introduces a detailed analysis of black shells with perfect fluid matter, focusing on their observable mass and dependence on physical parameters, which is a novel approach.

Findings

Observable mass depends on sound speed, radial velocity, and surface density.

Black shells exhibit distinct features based on their equation of state.

The study provides insights into the structure of horizon-sized fluid shells.

Abstract

The spherically symmetric singular perfect fluid shells are considered for the case of their radii being equal to the event horizon (the black shells). We study their observable masses, depending at least on the three parameters, viz., the square speed of sound in the shell, instantaneous radial velocity of the shell at a moment when it reaches the horizon, and integration constant related to surface mass density. We discuss the features of black shells depending on an equation of state.