object

torus

A doughnut-shaped ring of gas and dust surrounding a supermassive black hole.
53 related articles

Description

In the context of active galactic nuclei, a torus is a doughnut-shaped ring of gas and dust that surrounds a supermassive black hole. This structure plays a crucial role in the unified model of active galactic nuclei, explaining why some black holes appear as quasars while others are hidden from view. The torus absorbs optical and ultraviolet light from the accretion disk and re-emits it in the infrared, making it a key observational signature.

History

The torus concept was introduced in the 1980s as part of the unified model of active galactic nuclei, primarily through the work of Robert Antonucci and Joseph Miller.

How it works

The torus is thought to be fed by material falling toward the black hole, which forms a rotating, flattened structure due to conservation of angular momentum. The inner edge of the torus is heated by the accretion disk to temperatures of hundreds to thousands of kelvin, producing strong infrared emission. Depending on the viewing angle, the torus can obscure the central engine, leading to different observed classes of active galactic nuclei.

In practice

Crucial for interpreting observations of quasars and Seyfert galaxies, and for estimating the masses of supermassive black holes from infrared reverberation mapping.

Fun fact

The torus can be so thick that it completely hides the black hole's accretion disk from our line of sight, making the object appear as a 'type 2' AGN rather than a bright quasar.

Concept graph →

Related articles · 53

Mesoscale2026-08-121 minarXiv:2608.12285express
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Galaxies2026-08-111 minarXiv:2608.10719express
A Wanderer That Feeds on the Go
A black hole with a mass of 35,000 Suns drifts through a galaxy's gas like a barge through fog. Its gravity rakes the material ahead of it, leaving a dense trail behind — a wake of gas. Some of that gas gets pulled into the black hole, and it grows.
HEP Theory2026-08-102 minarXiv:2608.09797express
Black Hole Rings Like a Hot Bell
Drop a pebble into a pond, and ripples spread across the water. Something similar happens when a black hole merges with another: it emits gravitational waves that resemble the fading ring of a bell.
Stellar2026-08-102 minarXiv:2608.09896
Planetary Kitchens: What the Pantries of Taurus Hide
In the dark kitchen of the Taurus molecular cloud, 450 light-years away, dozens of planetary systems are being prepared. Each young star is a chef, and its protoplanetary disk is a counter piled with flour-like dust and steam-like gas.
General Relativity2026-08-092 minarXiv:2608.08711express
Energy from the void: how a star without a black hole amplifies light
A black hole pulls in anything that gets too close. But if you toss in not one object but a pair, one of them can fly back out, carrying off some of the hole's rotational energy. This trick, devised by Roger Penrose in 1969, works only because a black hole has a horizon — a boundary beyond which nothing returns. Now it turns out the horizon isn't necessary.
General Relativity2026-08-062 minarXiv:2608.05861express
Black hole in a dark matter cocoon
Somewhere in the center of a galaxy, a black hole is spinning. It doesn't hang in a void — around it swirls an invisible swarm of dark matter particles. Until now, this swarm was described for non-rotating holes, but in reality, holes always rotate.
A Pearl in a Dark Matter Shell
A neutron star is the ultra-dense remnant of a supernova: the mass of the Sun packed into a sphere the size of a city. For billions of years, it travels through space, gathering around itself invisible matter, dark matter, which emits no light but pulls with gravity.
General Relativity2026-08-031 minarXiv:2608.02051express
Dark Matter Around a Black Hole: A Torus-Shaped Cloud
A black hole isn't just a cosmic vacuum cleaner. If it rotates, it can amplify waves around it, much like a mountain echo repeats sound. For ultralight dark matter (particles billions of times lighter than an electron), this effect, called superradiance, can create a huge cloud.
High Energy2026-07-302 minarXiv:2607.27658express
Black Holes: Neutrino Factories
At the centers of many galaxies lurk giant black holes. They are surrounded by dense clouds of hot plasma that emit a powerful X-ray glow.
Galaxies2026-07-253 minarXiv:2607.22966
A Chick in a Dust Shell: How a Red Quasar Emerges
In the deep field of JWST, among thousands of galaxies, astronomers zoomed in on the source JADES-GS 209777 – and saw a cosmic chick. Its "shell" is a thick cocoon of gas and cosmic dust that long hid the growing black hole at its center. But at a redshift of 3,711 (1,8 billion years after the Big Bang), the shell began to crack.
The Dance of Gears: Why Some Black Holes Blow Winds and Others Shoot Jets
The fastest wind in the Universe travels at 0,58 times the speed of light. It covers the distance from Earth to the Moon in two seconds. This wind is not a jet stream but a broad flow of gas erupting from the center of a galaxy. Not all black holes work the same: some create such hurricanes, while others produce narrow plasma beams.
The Neutrino Aria of Black Holes: Listening in on Silent Dark Matter
Dark matter remains the inaudible bass line of the cosmic symphony — it emits no light, but its gravitational pull shapes galaxies. Vera Rubin first caught this rhythm in the 1970s by observing the rotation of stars.
General Relativity2026-07-122 minarXiv:2607.10713express
Black Holes Without Singularities: Almost Indistinguishable
An ordinary black hole hides a singularity at its center — a point where density and curvature become infinite and the laws of physics break down. The authors of the new work built a model of a rotating black hole that, instead of a singularity, contains a calm "core" resembling ordinary flat space.
General Relativity2026-07-102 minarXiv:2607.09201express
Tiny Black Holes Build Giants
The James Webb Space Telescope peered into an era when the universe was less than a billion years old and spotted strange objects—'little red dots.' These are black holes with masses of millions of suns, but in very compact, chemically pristine galaxies. Standard scenarios can't grow such heavyweights that early.
Exoplanets2026-07-041 minarXiv:2607.03866express
Dust Ring Instead of a Continuous Disk Around Planet PDS 70 c
When a giant planet grows, it pulls in gas. Some of that gas swirls around it into a small disk — called a circumplanetary disk. It is in such disks that moons are thought to form. For the planet PDS 70 c, located 370 light-years away, such a disk was directly observed using the ALMA antenna array in the millimeter range.
General Relativity2026-07-041 minarXiv:2607.03938express
A Black Hole as a Heat Engine
A black hole's interior is layered like an onion. In the new model, instead of an infinite point at the center, there are three regions: a dense core, a transition layer, and a crust just below the horizon. All arise from a single field that interacts with itself.
Galaxies2026-06-294 minarXiv:2606.30711
HEP Theory2026-06-291 minarXiv:2606.30794express
A Black Hole in a Fluffy Fur Coat
An ordinary black hole is surrounded by a thin photon sphere — a place where light can loop around before falling in or escaping. In the new work, this region has puffed up into a whole layer packed with massless particles that zip around at nearly the speed of light and don't press against the walls.
Galaxies2026-06-233 minarXiv:2606.24684
Dusty Crucibles: Only Bright Galaxy Cores Remember Mergers
In the boundless night of space, galaxies come together in a slow gravitational dance, merging into one. Such collisions are not head-on impacts but rather like fingers moving slowly through water, leaving swirls and tails behind.
HEP Theory2026-06-151 minarXiv:2606.16986express
Quantum Physics2026-06-112 minarXiv:2606.13383express
What a Black Hole Breathes
A bonfire doesn't burn out all at once. If you glance at the flames at a random moment, all you see is a jumble of fire tongues, and you can never tell what exactly burned: a wet branch, an old magazine, or an armful of dry grass. But if you watch the fire hour after hour, rhythms emerge in its dance: a burst of heat, a lull, a change in color. These rhythms tell the story of what was thrown into the flames.
Galaxies2026-06-043 minarXiv:2606.06620
Roots of the Cosmic Banyan: How Black Holes Feed
Cosmic black holes at the centers of galaxies are like giant banyan trees: their aerial root‑filaments stretch for kiloparsecs to harvest nourishing matter. For decades astronomers have debated: how does cooling gas from cluster atmospheres fall into the sphere of influence of a supermassive hole?
Cosmology2026-06-023 minarXiv:2606.03414
General Relativity2026-05-281 minarXiv:2605.30145express
Dark Matter Sculpts Black Holes
Just a few hundred million years after the Big Bang, in the ocean of invisible dark matter, giant black holes were already taking shape. They were born from the matter itself — without any help from stars. This mechanism, based on the equations of Lemaître, explains their early appearance.
General Relativity2026-05-271 minarXiv:2605.28376express
Shadow of a Shaggy Beast: How Scalar Hair Shatters a Black Hole’s Image
A black hole isn’t a perfectly smooth ball. Einstein’s theory allows invisible 'hair' — clumps of scalar field — to swarm around it, warping spacetime. The shadow — the dark region from which light can’t escape — was predicted by Penrose in the 1960s.
Galaxies2026-05-202 minarXiv:2605.21589express
Red dots and the magnetic cocoon of a black hole
A powerful vacuum cleaner sucks in not only dust but also its own collection bag. That's roughly how a black hole behaves at the center of a 'red dot'—a distant galaxy where the glow comes not from the hole itself but from its dense gas shroud. This shroud is so thick it resembles a puffed-up cool star. And, like many stars, it has a magnetic field.
General Relativity2026-05-112 minarXiv:2605.10874express
Black Holes Latch Onto Each Other with Beaks
Two black holes fly toward each other and collide head-on. In the familiar picture, their horizons (the surfaces from which not even light can escape) stretch toward each other like water droplets and merge into one smooth shape. But calculations show otherwise: before merging, a sharp beak, a cusp, extends from each horizon.
General Relativity2026-04-302 minarXiv:2604.27880express
Black Hole with a Fluffy Core
A pencil dropped on the floor hits with its entire surface at once. But if the floor were quantum, made of countless vibrating grains of sand, the pencil would never touch a single point.
General Relativity2026-04-222 minarXiv:2604.20066express
General Relativity2026-04-221 minarXiv:2604.20499express
The Shadow of a Black Hole Changes Shape
A black hole is not just a dark sphere in space. If there is gas and dust nearby, they swirl into a flat, glowing disk that gradually falls inward. This disk acts like a lamp, illuminating the hole itself, and against the bright background you can see its shadow — a dark silhouette with sharp edges. But what if the disk is not flat but torn into pieces?
Galaxies2026-04-201 minarXiv:2604.17955express
Gas Jumps Over the Ring
A river flows toward a whirlpool, but a dam with a notch blocks the way. Most water piles up before the dam, but some, gaining height, leaps over it and falls straight into the funnel. So it is with gas in a galaxy: it streams toward the center but hits a ring of stars and gas, like a dam. Usually, everything stops there, swirling into a dense vortex.
Cosmology2026-03-311 minarXiv:2603.29790express
Invisible Cloud Steals Spin from Black Holes
Tiny black holes, born right after the birth of the universe, are supposed to evaporate — shedding mass as invisible particles. This was predicted by Stephen Hawking, and this 'Hawking evaporation' contributed to the expansion of the young cosmos.
High Energy2026-03-221 minarXiv:2603.21307express
The Explosive Letter S: How a Dying Star Draws Loops in Space
In a gas cloud left after a star exploded (called a supernova remnant), astronomers noticed a giant glowing letter S. It was drawn by two jets of superheated material ejected during the cataclysm. These jets didn't just shoot straight out — they slowly spun like a top, which bent their path into curves.
Galaxies2026-02-252 minarXiv:2602.21502express
A Galaxy Wakes Up Before Our Eyes
Deep in the constellation Ophiuchus lies the galaxy NGC 6447. Until recently, it was quiet and unremarkable, like a house with its windows dark. But over the past 14 years, something has ignited at its center, and now it's visible in infrared light.
Galaxies2026-02-251 minarXiv:2602.22366express
Exoplanets2026-02-181 minarXiv:2602.16816express
The Planet That Wrapped Its Star
A planet hugging its star is like an ice cube forgotten on a scorching skillet. The ice melts and evaporates, except instead of water, it's hydrogen and helium from the planet's upper layers.
Galaxies2026-02-171 minarXiv:2602.15940express
Dark Matter Opens Its Arms
The James Webb Space Telescope peered into the galaxy cluster AS1063 and spotted tens of thousands of globular clusters — dense stellar "knots" scattered throughout the cluster. Their positions matched the map of invisible mass, which is constructed from the bending of light from distant galaxies.
Quantum Gases2026-02-162 minarXiv:2602.14549express
Atoms in a Ring: How to Make a Bagel of Light and Magnetism
A tiny cloud of atoms, cooled to millionths of a degree above absolute zero, floats in a ring-shaped trap. It looks like a glowing necklace, but physicists have made it live on the surface of an invisible bagel. Using laser beams and microwave pulses, three internal states of the atoms were linked into a cycle.
General Relativity2026-02-141 minarXiv:2602.13609express
A black hole can turn into a wormhole
An ordinary black hole is a bottomless pit from which not even light can escape. However, physicists have found a way to turn this pit into a through-tunnel — a wormhole.
Galaxies2026-02-131 minarXiv:2602.12661express
A Ring of Warmth in a Star's Cradle
In a cold, dark cloud of gas where a star is just beginning to form, the ALMA telescope has spotted an unusual ring. It is made of gas that is warmer and denser than its surroundings. Such details were previously hidden because the gas at the cloud's center is opaque to ordinary observations.