This map made from the LOFAR survey shows supermassive black holes clustered in the Universe. The … [+]
LOFAR LBA Sky Survey / ASTRON
A large enough mass in a compact volume inevitably forms a black hole.

Both inside and outside the event horizon of a Schwarzschild black hole, space flows like either a … [+]
Andrew Hamilton / JILA / University of Colorado
In 1964, we observationally detected our first one: Cygnus X-1.

The X-ray emitter Cygnus X-1, in the constellation of Cygnus, as imaged by a balloon-borne … [+]
NASA / Marshall Space Flight Center
Black holes emit no light, but numerous physical processes can still reveal them.

Cygnus X-1, at left, is an X-ray emitting black hole orbiting another star. Located ~6,000 … [+]
Optical: DSS; Illustration: NASA
Matter infalling into a black hole’s vicinity forms accretion disks.

A black hole feeding off of an accretion disk. It’s friction, heating, and the interplay of charged … [+]
Mark Garlick (University of Warwick)
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Once sufficiently heated, that matter emits X-ray light.

When a black hole accretes matter, it grows an accretion disk and will increase its mass as matter … [+]
NASA/ESA Hubble Space Telescope collaboration
These “X-ray binaries” revealed humanity’s first black holes.

The first black holes were detected electromagnetically: as X-ray binaries. The purple points show … [+]
LIGO/VIrgo/Northwestern Univ./Frank Elavsky
Supermassive black holes also produce X-rays.

The supermassive black hole at the center of our galaxy, Sagittarius A*, flares brightly in X-rays … [+]
X-ray: NASA/UMass/D.Wang et al., IR: NASA/STScI
NASA’s Chandra discovered thousands in its ultra-deep images.

A map of the 7 million second exposure of the Chandra Deep Field-South. This region shows hundreds … [+]
NASA/CXC/B. Luo et al., 2017, ApJS, 228, 2
Energetic black hole outflows create positrons: the electron’s antimatter counterpart.

On either side of the plane of the Milky Way, enormous gamma-ray bubbles are being blown. The energy … [+]
NASA/Goddard Space Flight Center
These ejecta generate “Fermi bubbles” around galactic centers, including our own.

In the main image, our galaxy’s antimatter jets are illustrated, blowing ‘Fermi bubbles’ in the halo … [+]
David A. Aguilar (main); NASA/GSFC/Fermi (inset)
Additionally, gravitational waves reveal inspiraling and merging black holes.

Two black holes of approximately equal mass, when they inspiral and merge, will exhibit the … [+]
N. Fischer, H. Pfeiffer, A. Buonanno (Max Planck Institute for Gravitational Physics), Simulating eXtreme Spacetimes (SXS) Collaboration
But radio studies uncover black holes most abundantly.

This X-ray/radio composite shows a supermassive black hole actively feeding within a distant galaxy. … [+]
X-ray: NASA/CXC/KIPAC/N. Werner et al Radio: NSF/NRAO/AUI/W. Cotton
Infalling matter around black holes commonly produces radio waves.

This is an artist’s impression of a distant quasar 3C 279. The bipolar jets are a common feature, … [+]
ESO/M. Kornmesser
This explains the origin of quasars: QUAsi-StellAr Radio Sources.

The Pictor A galaxy has a supermassive black hole at its center, and material falling onto the black … [+]
X-ray: NASA/CXC/Univ of Hertford
Supermassive, active black holes emit tremendously powerful radio signals.

When hot gas actively falls onto the central black hole within a galaxy, a quasar can be produced. … [+]
NASA/CXC/Penn. State/G. Yang et al and NASA/CXC/ICE/M. Mezcua et al.; Optical: NASA/STScI; Illustration: NASA/CXC/A. Jubett
The 52-station LOFAR array just synthesized an unprecedented set of radio data.

Installation Manager Derek McKay checks some of the 96 radio antennae installed for the new European … [+]
PA Images via Getty Images
Spanning 740 square degrees, they found 25,247 supermassive black holes.

The survey area and the detected signals (in surface brightness) of the LOFAR telescope. Covering … [+]
F. de Gasperin et al. (2021), arXiv:2102.09238
This data reveals the clustering of galaxies; every point is a black hole.

When quasar orientation can be observed and identified, it is found that they align in a non-random … [+]
ESO/M. Kornmesser
LOFAR will eventually survey the entire northern hemisphere, expecting ~600,000+ identifiable black holes.

Thus far, LOFAR has only observed where the yellow dots are indicated: about 2% of the total sky. By … [+]
F. de Gasperin et al. (2021), arXiv:2102.09238
Observationally abundant, black holes aren’t purely theoretical anymore.

This 20-year time-lapse of stars near the center of our galaxy comes from the ESO, published in … [+]
ESO/MPE
Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less; smile more.