red galactic nuclei

The night sky looks serene, but it is actually pierced by an invisible rain of charged particles: cosmic rays. Scientists have long tried to figure out where the most energetic ones are born. Until recently, it was thought that our Galaxy supplies particles up to about 4 EeV, the so-called "ankle" in the spectrum.

At the center of the Milky Way, where the supermassive black hole Sagittarius A* churns gas clouds like a millstone, astronomers have caught an irregular pulse. Gamma-ray emission, the most energetic light in the universe, arrives not as a smooth wave but with a break, as if the Galaxy's heart beats with arrhythmia.

The night sky looks calm, but in reality, invisible particles, cosmic rays, are constantly flying through us. Among them are electrons and their antimatter counterparts, positrons. When they collide with detectors on satellites or balloons, the instruments record their energy.

Light escaping a massive body loses steam. Its frequency dips slightly, and its color shifts toward red. Physicists call this gravitational redshift. In classical theory, it's all clear, but the moment you bring quanta into the picture, trouble starts. Previously, this shift was modeled as a kind of mode mixer — a device that entangles different states of light.

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 invisible hand of dark matter squeezes galaxies in gravity's embrace, yet its nature has remained elusive for nearly a century.

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.

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.

A translator gets distracted by every rustle in the hall, and a one-hour meeting stretches into two. Gluons, the particles that carry the strong force inside protons, behave much the same way. Usually, they dart back and forth, holding quarks together.

A powerful searchlight shines through thick fog. The beam itself is invisible, but the fog begins to glow faintly, and gives away the searchlight's presence.

Eight red giants — bloated old stars like the future Sun — are not behaving by the book. Their surfaces oscillate steadily, like a bell, but within this chime there are glitches: some tones are missing, and the rhythm breaks. Scientists suspected an invisible hand inside — a magnetic field — and tried to calculate its strength.

A radio telescope picks up a signal from the center of the Milky Way. The source MAXI J1744-294 flares in X-rays and radio waves, but where it actually resides is a mystery. It could be near the black hole, or it could just lie along the same line of sight, thousands of light-years away.

In the galaxy NGC 1566, located in the constellation Dorado, there is an active nucleus — a supermassive black hole surrounded by a cloud of fast-moving gas. As the gas falls toward the hole, it heats up and emits bright spectral lines. Sometimes these lines become very broad — a sign of the gas's rapid rotation.

At the heart of galaxy NGC 4051 lies a black hole with a mass of 800,000 Suns. Around it swirls a blazing hot gas that shines brightly. This light doesn't reach us all at once: blue rays arrive first, then green, then red.

Gamma rays with energies above one hundred trillion electronvolts are like stones thrown with incredible force. For a long time, it was believed that only protons, heavy particles accelerated in cosmic accelerators, could launch such 'stones.' But new work shows that sometimes light electrons are enough.

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.

At the center of galaxy NGC 4278 sits a black hole that shoots out two plasma jets, like a giant cannon firing particles into space. These jets accelerate particles to energies that no earthly accelerator could ever dream of.

A city at night looks quiet from above, but life bustles in its neighborhoods: streets are blocked off, construction is underway, and equipment hums in basements. That's roughly how astronomers now see the galaxy cluster SPT-CL J2215-3537, located so far away that its light has traveled for more than 8 billion years.

Light from a distant source passing near a neutron star bends like a flashlight beam in a funhouse mirror. Astrophysicists ran a numerical experiment: they traced rays backward from the observer to the star and looked at what picture a telescope would see.

Every day, particles with colossal energy enter Earth's atmosphere, like unsigned letters. Their source long remained a mystery. New research shows: these 'visitors' point to nearby galaxies, where from time to time catastrophes occur — collisions of neutron stars, ultra-dense spheres the size of a city but with the mass of the Sun.

The James Webb Space Telescope has spotted a scattering of compact objects in the early universe, nicknamed 'little red dots.' They are too red and too dim to be ordinary quasars, and astrophysicists are scratching their heads over what powers them.

Cosmic rays are atomic nuclei accelerated to near-light speeds. They arrive at Earth from all directions, and their composition tells us what's happening in the far reaches of the Galaxy.