Lower bound on the mass of a black hole

TL;DR

This paper establishes a lower bound on black hole mass by analyzing the limitations of low-energy effective theories involving massive fields, concluding that black holes must exceed 10^{14} kg in four dimensions.

Contribution

It introduces a novel method linking quantum perturbation breakdown to a minimum black hole mass in low-energy gravity theories.

Findings

Black holes in four dimensions must be heavier than 10^{14} kg.

Quantum perturbation growth limits the trustworthiness of effective actions.

A new lower bound on black hole mass derived from quantum field considerations.

Abstract

We consider gravity coupled to a massive field whose Compton's wavelength is far larger than the Planck's length. In the low energy effective action for gravity, thus, it is the perturbation in the Compton's wavelength that breaks first as the sub-sub-leading quantum perturbation grows stronger. When this break occurs, we can not trust the perturbative information about the form of the low energy effective action. We translate this break into the lowest limit on the mass of a classical black hole. In D=4, using the electron's mass, this requires the black hole to be heavier than 10^{14} kg.