Behavior of Phantom Scalar Fields near Black Holes

TL;DR

This study investigates how phantom scalar fields affect black hole horizons, demonstrating rapid black hole shrinking due to accretion, with the scalar field's equation of state varying significantly over space and time.

Contribution

It provides the first detailed numerical analysis of phantom scalar field accretion onto black holes in the full non-linear regime, revealing efficient horizon mass reduction.

Findings

Black hole apparent horizon mass decreases during phantom scalar field accretion.

The horizon area reduction occurs on short time scales.

The scalar field's equation of state varies with space and time, typically exceeding -1.

Abstract

We present the accretion of a phantom scalar field into a black hole for various scalar field potentials in the full non-linear regime. Our results are based on the use of numerical methods and show that for all the cases studied the black hole's apparent horizon mass decreases. We explore a particular subset of the parameter space and from our results we conclude that this is a very efficient black hole shrinking process because the time scales of the area reduction of the horizon are short. We show that the radial equation of state of the scalar field depends strongly on the space and time, with the condition $\omega = p/\rho>-1$, as opposed to a phantom fluid at cosmic scales that allows $\omega < -1$.