mass distribution

A million orbits: the same score. Nine dark matter halos: nine orchestras without a conductor. All musicians play from the same notes, but in each hall the music sounds different: sometimes in tune, sometimes out of sync. Likewise, satellite galaxies falling into a host halo follow orbits that depend not only on mass but also on the shape of the invisible stage.

Think of a merry-go-round: the farther you sit from the center, the faster you're carried around. For a long time, astronomers assumed galaxies work the same way — stars at the edges should orbit more slowly than those near the center. But back in the 1970s, it turned out that in many spiral galaxies, the speed of stars barely drops with distance from the center.

A galaxy is like a city: bright lights and dense buildings at the center, sparse lights and emptiness toward the outskirts. But if you watch how gas rotates in a galaxy's disk, you see that its speed barely drops at the edges. As if invisible neighborhoods keep the motion going. Astronomers have found a way to map this invisible city.

The early Universe was not just a hot soup of particles. In the first fractions of a second, mirror symmetry could have been broken: the world and its reflection would not be quite identical. If so, the large-scale cosmic web of galaxies would retain a barely noticeable 'curl'—as if all matter were slightly twisted in one direction.

In the galaxy NGC 1052 DF2, stars move at only 8 kilometers per second, as if there were no invisible mass around. For comparison: in our Milky Way, outlying stars accelerate to 200 kilometers per second, held by a massive dark matter halo.

Two balls dropped from different heights fall to the ground with different accelerations. In space, things are more complicated: even emptiness makes bodies move differently.

Dark matter — the invisible foundation of cosmic architecture — makes up 85% of all mass, yet eludes direct observation. In the 1920s, Edwin Hubble discovered the expansion of the universe and the realm of galaxies; by the 1930s, Fritz Zwicky suspected hidden mass in their clusters.

At the center of a tiny galaxy lies a dense clump of stars and dark matter. This clump, called a soliton, is not frozen in place: it quivers and oscillates like jelly on a plate.

At the center of the Milky Way, like a matryoshka doll within a matryoshka doll, lies a supermassive black hole, surrounded by a swarm of stars and an invisible shell of dark matter. This shell, or "spike," is expected to be extremely dense right at the horizon.

Photographing the vicinity of a black hole is like shooting a fountain: a short exposure freezes the droplets, a long one blends everything into blurry streaks. Light from the superheated gas swirling around the hole reaches us along different paths. Some rays curve around it in an arc, others make multiple loops due to spacetime curvature.

When light swings past a massive body like a black hole, its path warps — an effect predicted by Einstein. New research has taken into account that near such objects, clouds of hadrons often swirl — the very particles we know from protons and neutrons in atomic nuclei.

A pebble drops into a pond, and neat circles spread across the water. But the pond's bottom is strewn with invisible glass shards: each one slightly delays the wave, scatters it here, or alters its pace. That's roughly how gravitational waves, the trembling of space itself, pass through distant galaxies and dark clumps of matter.

Two galaxy clusters collided like two swarms of bees flying through each other. One of them is the famous "Bullet." After the collision, the hot gas, which makes up most of the ordinary matter, slowed down and stayed in the center, while the galaxies, like small dense pebbles, flew on.

Previously, astronomers calculated galaxy mass as if they were perfect spheres. But a galaxy is a flat pancake. The new 'Lost and Found' model takes the actual shape into account: it sums up the gravitational pull from all parts of the disk, not just the central bulge. The result is stunning: many galaxies need a third less invisible dark matter than previously thought.

Every galaxy is wrapped in an invisible shell of hot gas, like steam rising from a pot of boiling water. This gas barely glows in X-rays, making it notoriously difficult to measure. Yet it holds the memory of stellar explosions and the galaxy's growth. The new method uses light from a galaxy's bright center.

A galaxy is like a giant merry-go-round: stars and gas whirl around the center, and their speeds reveal how much stuff is on the ride. If we only saw the luminous matter, the outer parts would spin slower than observations show. So there must be invisible mass, dark matter, that holds the galaxy together.

In the constellation Cetus, 65 million light-years from Earth, three dwarf galaxies nestle: DF2, DF4, and DF9. All have been declared “galaxies without dark matter” — the mysterious invisible substance that usually holds stars together.

Images of distant galaxies are riddled with curved arcs and smears — light warped on its way to us. This effect, predicted by Albert Einstein, acts like a giant funhouse mirror: a massive galaxy cluster distorts the images of background sources.

Schrödinger's cat, according to quantum rules, can be both alive and dead at once. But a table can't pull that off. When a massive object tries to be in two places, its mass curves spacetime so drastically that instead of two points, a single deep depression forms, and the object rolls into it.

At the center of our Galaxy lies a supermassive black hole, with stars orbiting around it. Their motion resembles a cosmic dance: some race along elongated orbits, others follow nearly circular paths. If invisible dark matter exists near the black hole, it slightly distorts these orbits, like an unseen hand nudging a star off course.

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.

The night sky is full of stars, but they are only a small part of everything that exists in the universe. Astronomers have long noticed a strange thing: galaxies rotate so fast that they should fly apart, yet they don't. Something invisible holds them together, like invisible threads linking beads on a spinning wheel. This "something" was named dark matter.

Three distant galaxies spin like giant carousels. Their stars and gas move along spiral arms, and from the speed of this motion you can calculate how much total matter the galaxy contains — visible and invisible. Astronomers combined two views: radio telescopes revealed cold gas, while the James Webb Space Telescope showed the stars.

Supermassive bodies warp space, turning into a lens that bends light from distant objects. Such spacetime curvature allows astronomers to see the invisible. Recently, this method helped detect a hidden clump with the mass of a million Suns.

The Milky Way's stellar disk is like a glowing pinwheel, and тёмное вещество is an invisible cloud around it. For the first time, its shape has been precisely measured. Astronomers tracked the motions of millions of stars and built a 3D map of the тёмное гало out to 160,000 light-years.