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Black holes were theoretically established in 1915, shortly after Albert Einstein published his theory of General Relativity. Since then, observations have confirmed black holes as actual astrophysical objects. In this Insight we publish ten long- and short-format pieces (in the “Reviews & Perspectives” and “Views & Comments” tabs, respectively) discussing key aspects of black holes, from their masses, to their spins, to the ways in which they impact their surroundings and are studied. This collection also showcases some of the black hole-related content that Nature Astronomy has published since our launch (in the “Primary research” and “Further reading” tabs). Also, please view our previous collection of landmark black hole discoveries published in Nature and other Springer Nature journals.
Black holes have the distinct honour of being the most popular and potentially the least well-understood objects in the Universe. This issue’s Insight explores how far black hole research has come since its inception, though it still has a long way to go.
Mitchell C. Begelman, Professor in the Department of Astrophysical and Planetary Sciences at the University of Colorado Boulder and a black hole expert, discusses the start of the field with Nature Astronomy.
Intermediate-mass black holes (BHs) in local dwarf galaxies are considered the relics of the early seed BHs. However, their growth might have been impacted by galaxy mergers and BH feedback so that they cannot be treated as tracers of the early seed BH population.
The masses of supermassive black holes, key to many cosmological studies, are highly uncertain beyond our local Universe. The main challenge is to establish the spatial and kinematic structure of the broad-line emitting gas in active galactic nuclei.
The detection of a gravitational-wave background at nanohertz frequencies can tell us if and how supermassive black holes merge, and inform our knowledge of galaxy merger rates and supermassive black hole masses. All we have to do is time pulsars.