Black hole astronomy

Black hole astronomy studies black holes through their gravitational effects, surrounding matter, and emitted radiation. It combines observations across the electromagnetic spectrum with gravitational-wave and other measurements.

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Accretion disk: A rotating structure of gas and dust that spirals toward a massive central object while friction heats it. Its intense radiation makes feeding black holes observable.
Event Horizon Telescope: A global network of radio telescopes that uses very long baseline interferometry to image horizon-scale structures. It produced the first resolved images of black hole shadows.
General relativity: Albert Einstein’s theory describing gravity as the curvature of spacetime caused by energy and matter. It predicts black hole structure and the motion of matter near it.
M87*: The supermassive black hole at the center of the galaxy Messier 87. Its 2019 Event Horizon Telescope image revealed a bright ring around a central shadow.
Black hole formation: The physical processes by which collapsing stars or other dense systems create black holes. Formation pathways determine which masses and spins astronomy should find.
Relativistic jet: A narrow outflow of particles moving near light speed, launched from regions around some compact objects. Jets carry energy far beyond the black hole’s immediate surroundings.
X-ray astronomy: The study of celestial sources through their X-ray emission. Hot gas near stellar-mass black holes often shines strongly in X-rays.
Schwarzschild metric: An exact solution of Einstein’s field equations describing spacetime outside a spherical, nonrotating mass. It supplies the simplest model for estimating a nonrotating black hole’s gravitational effects.
LIGO–Virgo–KAGRA: An international network of interferometric observatories that detects gravitational waves. Its detections established a population of merging stellar-mass black holes.
Intermediate-mass black hole: A hypothesized or candidate black hole with a mass between stellar-mass and supermassive black holes. Evidence for this population remains sparse compared with the two better-established mass ranges.