Testing the black hole "no-hair" hypothesis

TL;DR

This paper reviews the no-hair hypothesis of black holes, discussing how it can be tested through electromagnetic and gravitational observations to probe fundamental physics and the nature of the universe.

Contribution

It provides an overview of methods to measure black hole 'no-hair' properties and explores their implications for fundamental physics.

Findings

Black holes are characterized by a few parameters, supporting the no-hair hypothesis.

Observational techniques can test deviations from the no-hair conjecture.

Measuring black hole properties can reveal new physics beyond General Relativity.

Abstract

Black holes in General Relativity are very simple objects. This property, that goes under the name of "no-hair," has been refined in the last few decades and admits several versions. The simplicity of black holes makes them ideal testbeds of fundamental physics and of General Relativity itself. Here we discuss the no-hair property of black holes, how it can be measured in the electromagnetic or gravitational window, and what it can possibly tell us about our universe.