radio source

At the heart of nearly every large galaxy sits a supermassive black hole. Usually it behaves quietly, but sometimes, like a waking volcano, it spits out narrow plasma jets. These jets glow in the radio band, making the galaxy 'radio-loud.' Astronomers have long known this happens, but they couldn't catch the very moment of switching on.

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.

Imagine a lottery where instead of money, you win black holes. Each ticket is a random spot on the sky, and the prize is a gravitational wave from the merger of two giants. The chance of hitting the jackpot is minuscule, but if you do, the wave is heard across the entire universe.

A radio telescope, like a sensitive ear, picks up the whispers of distant galaxies. Hidden among that noise are giants — giant radio sources. These are clouds of charged particles ejected from the vicinity of supermassive black holes.

A lighthouse that blinks not every second but once every few minutes or even hours. That is exactly how long-period radio transients behave — cosmic sources discovered only recently.

Somewhere in the depths of the Milky Way, radio pulses flare up from time to time — rare, steady, like the ticks of a distant metronome. These long-period radio transients were discovered only recently, and they immediately puzzled astronomers.

At the end of a massive star's life, its core collapses in a fraction of a second, giving birth to a supernova flash. This cataclysm shakes spacetime itself, emitting gravitational waves — ripples that race across the Universe.

When a star many times heavier than the Sun dies, it collapses and explodes as a supernova. This is not just a flash of light — the entire process, from core collapse to the ejection of the outer layers, makes space itself tremble. These ripples are called gravitational waves.

The mystery of antimatter in space has long puzzled astrophysicists: where do positrons come from, settling like snowflakes into our detectors? The answer might lurk in the most ubiquitous gamma-ray background. The Universe is soaked in diffuse light — the cosmic photon background (CPB).

A low rumble coming from underground could be the noise of a distant construction site, or it could be the echo of an ancient earthquake. Astronomers faced a similar puzzle in 2023 when they detected ultra-low-frequency gravitational waves — the trembling of spacetime itself, rippling across the universe.

Somewhere deep in space, a radio beacon flashes for a fraction of a second, and then goes dark. Such signals are called fast radio bursts. They come from other galaxies and last from microseconds to milliseconds.

Light passes through a crumpled film — and comes out slightly altered. In much the same way, gravitational waves born in the early universe feel the lumpy distribution of galaxies and dark matter.

Gravitational waves are ripples in the very fabric of spacetime, akin to vibrations of a giant cosmic string. Conventional detectors like LIGO and Virgo pick up low-frequency "notes"—disturbances from mergers of massive black holes of stellar masses.

Astronomers listen to the cosmos like an old radio: they twist the knob not to find a particular station, but to catch any unusual noise. This approach breaks the mold: instead of hunting for gravitational waves using memorized patterns, they catch everything — without bias.

Gravitational waves are ripples in space from the mergers of black holes and neutron stars. Existing detectors, built with contributions from Kip Thorne and Rainer Weiss, work like highly sensitive microphones but only hear the highest 'notes'.

The first exoplanet was discovered around an unusual cosmic lighthouse — a neutron star known as a pulsar. These ultra-dense remnants of dead stars spin at tremendous speeds and emit precise radio pulses.

Einstein and Rosen imagined a bridge connecting two sheets of reality. Wheeler gave it a name — wormhole, and Thorne with Morris proved: the tunnel is traversable if you fill it with exotic matter.

The fabric of space bends under weight, like a stretched trampoline. Gravitational waves — ripples spreading from cosmic cataclysms, such as merging black holes. If such a ripple encounters a massive galaxy or invisible dark matter, they act like a magnifying glass: bending and amplifying the signal.

Searching for extraterrestrial signals is like trying to hear a whisper at a roaring stadium. The Green Bank Telescope listened to 70,000 stars, but 100 million bursts turned out to be earthly noise — from phones, satellites, microwave ovens.

A stone falls into a pond — near the shore, the ripples are barely visible, while the water churns at the point of impact. The electric field around a charge behaves similarly: close in, it's sharp and tangled, but at a distance it stretches into a smooth wave that carries energy away. Physicists call this distant region the radiation zone.

Two neutron stars spiral closer together, about to merge in an instant. Their dance lasts fractions of a second, but just before the finale, one star plows into the other's magnetic envelope, like a swimmer cutting through water, kicking up waves. At that moment, a complex system of currents is born, carrying energy away.

The ASKAP radio telescope in Australia has spotted a very faint glowing ring in the southern sky, like a soap bubble the size of several full moons. Inside the ring, exactly at the center, shines a tiny point. Usually, such a picture means one thing: a star exploded here, leaving behind an expanding shell and a collapsed core at its heart. But this pair has a quirk.

A radio signal travels from Mars to Earth, but on the way it has to push through the invisible "wind" of charged particles blowing from the Sun. This wind, like ripples on water, slightly distorts radio waves.

Radio telescopes have caught a signal that repeats like a beacon in the fog. It's a fast radio burst — a brief flash of radio waves from a distant galaxy. Nearby, astronomers search for a persistent source — a faint glow that lingers after the burst, like embers after fireworks.

The night sky is full of beacons that blink on schedule. Pulsars are fast-spinning neutron stars whose radio pulses arrive with clockwork precision. But there are other beacons too: they stay silent for minutes or hours, then suddenly emit a single pulse, and go quiet again.

When a massive star dies, a supernova explosion occurs, so powerful that a single flash outshines an entire galaxy. In this fire, billions of axions are born — invisible particles that leave almost no trace. Every second, trillions of these tiny things fly right through each of us, completely unnoticed.

Plain water in a glass is clear and calm. But if you add tiny carbon dots made from sugar and citric acid in an ordinary microwave, the water starts to glow when a charged particle flies through it.

After a supernova explosion, a neutron star neutron star remains: a city-sized ball of unimaginably dense matter, spinning hundreds of times per second. Any tiny bump on its surface would make it wobble like an off-balance spinning top, humming faintly through the fabric of space.

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.

The solar corona, the Sun's outer atmosphere, stretches millions of kilometers, yet it's visible only during a total eclipse or with specialized instruments. Typically, we gauge the corona's density by how it scatters white light, but that method relies on simplifications that can skew the results.

A radio telescope has caught signals from three galaxies that existed when the universe was less than a billion years old. Their radio glow is so powerful that each seems to be birthing a thousand suns per year in a short span. For comparison, our Milky Way produces only a couple of stars per year.

The night sky is full of beacons, but some shine in a way that makes them nearly invisible. Astronomers have discovered a new class of objects: ultrasoft X-ray sources. They are so "cool" by X-ray standards that their emission falls at the boundary between ultraviolet and soft X-rays, where ordinary telescopes are almost blind.

Cosmic particles with energies millions of times greater than anything our accelerators can produce slam into the atmosphere and create a shower of secondary particles. This shower emits radio waves that antennas on the ground pick up. But the signal is weak: it's swamped by the radio noise of our galaxy and the receivers' own noise.

Astronomers nicknamed them 'little red dots' — distant galaxies where a giant black hole hides at the center, wrapped in a thick layer of hydrogen. This packaging isn't just camouflage; it's a natural cannon. The black hole sucks in matter, but some of it is spat back out in narrow jets.

Road noise is a great informant. Rare cars sound as individual signals; dense traffic merges into a steady hum. Just the same, mergers of black holes produce either single bursts or a continuous background of gravitational waves.

Neutrinos are ghost particles: predicted by the Standard Model, they barely interact with matter. Catching them is like trying to hear a whisper in the roar of a waterfall.

When a massive star exhausts its thermonuclear fuel, its core collapses and the outer layers are blown off in a colossal explosion — a supernova (a term coined by Fritz Zwicky while studying these catastrophes).

The solar wind isn't a calm stream but a bubbling soup of charged particles. Diving close to the Sun, the Parker probe picked up two types of stirring waves. Left-handed ones, like a whisk in a chef's hand, whip up the material when the temperature differs along and across the flow.

When a massive star exhausts its thermonuclear fuel, its core collapses, and the outer layers are ejected into space at speeds of thousands of kilometers per second. This is how a supernova remnant is born — an expanding cloud of shock-compressed gas spanning light-years.

The Moon is not just a satellite; it is a potential gravitational bell. When massive bodies collide, spacetime shudders, and that shudder, gravitational waves, makes everything in their path vibrate.