Can an evolving Universe host a static event horizon?

TL;DR

This paper proves the existence of dynamic black hole solutions with static event horizons in general relativity, particularly for perfect fluids with specific equations of state, challenging traditional static assumptions.

Contribution

It demonstrates that black holes with perfect fluid matter can have static horizons while remaining globally time-dependent, bypassing known no-go theorems.

Findings

Existence of perfect fluid black hole solutions with static horizons.

Time dependence of black hole configurations away from the horizon.

Global Hawking periodicity on the entire spacetime manifold.

Abstract

We prove the existence of general relativistic perfect fluid black hole solutions, and demonstrate the phenomenon for the $P=w\rho$ class of equations of state. While admitting a local time-like Killing vector on the event horizon itself, the various black hole configurations are necessarily time dependent (thereby avoiding a well known no-go theorem) away from the horizon. Consistently, Hawking's imaginary time periodicity is globally manifest on the entire spacetime manifold.