The hole picture

TL;DR

This paper discusses the observational evidence for black holes through electromagnetic and gravitational-wave data, highlighting how recent datasets provide insights into their environment, origin, and growth despite the inherent difficulty in proving their existence.

Contribution

It reviews recent observational datasets that offer new understanding of black holes' properties and origins, despite the fundamental challenge of directly proving their existence.

Findings

Observations have provided important clues about black hole environments.

Recent datasets shed light on black hole origins and growth.

Electromagnetic and gravitational-wave data complement each other in black hole studies.

Abstract

Because of the very definition of black holes --- no light escapes them and falling objects get infinitely faint when approaching --- it is impossible to ever prove that they exist. However, electromagnetic and gravitational-wave observatories have now `seen' black holes. Datasets from these observations, released in 2019 and late 2018, give important hints about the environment, origin and growth of black holes.