astrophysical magnetic fields

The map of dense nuclear matter resembles a road map: lines of phase transitions cross at critical points, like highways at intersections. Until now, only two intersections were known on such a map: the nuclear liquid-gas and deconfinement, where hadrons dissolve into quarks.

At the center of a neutron star, matter is compressed so tightly that a teaspoon weighs a billion tons. You'd think there's no better place to look for signs of quantum gravity. But between the laboratory and the fundamental scale lies a chasm of 10⁸⁰ in density. Three doors lead into this room.

Right after the Big Bang, space cooled unevenly. In some places, folds could have formed — threads of energy as thin as a hair but incredibly dense. Physicists call them cosmic strings. They oscillate, collide, and emit gravitational waves — ripples in the fabric of space itself.

An inflatable balloon with magnetic field lines drawn on it with a marker is a simple model of how a weak magnetic field behaves in an expanding universe. While the balloon is small, the lines lie obediently on the rubber and don't hinder its stretching. That's roughly how a field fills ready-made space without arguing with its geometry.

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.

In the depths of a neutron star, the remnant of an exploded star, matter is compressed so tightly that a teaspoon would weigh billions of tons. Within this superdense material, a special kind of force might be at work, one that affects only muon and tau neutrinos.

A neutron star is a sphere the size of a city but with the mass of an entire Sun. Its magnetic field can tear atoms apart from thousands of kilometers away. Yet until now, it was a mystery how this field is arranged inside: whether it is twisted into tight ropes or more like neat lines radiating from the poles.

A massive star collapses, and a black hole is born, surrounded by a disk of incandescent plasma. For narrow jets to burst out of this disk, an ordered magnetic field is needed. But inside the star, it's tangled.

A neutron star is the collapsed core of a massive star, squeezed to the size of a city. In its heart, matter is packed so densely that atoms cease to exist, and protons and neutrons dissolve into a sea of quarks.

A vast, dark cloud of gas stretched across the young universe. Inside it, like invisible fingers, magnetic field lines left over from the very birth of the cosmos threaded through. These fields act on charged particles, pushing them together, like a gentle breeze gathering fallen leaves into piles.

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.

Inside a neutron star, the density doesn't change smoothly but drops abruptly at sharp cliffs — density staircases. At these steps, the void suddenly births pairs: neutrinos and antineutrinos.

Two neutron stars — these are ultra-dense remnants of dead stars, each the size of a city but heavier than the Sun. Their existence was predicted back in 1934 by Fritz Zwicky. A teaspoon of this matter weighs billions of tons. When two such objects draw close before merging, their magnetic fields twist and snap like taut strings.

Imagine a tiny coin hidden inside a perfect safe, but the walls are so thin that the coin sometimes slips right through, leaving a barely audible sound. Axions are like those coins — except instead of metal, they're particles, and instead of a safe, they're ordinary matter. They barely notice obstacles, making them incredibly hard to catch directly.

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.

In a large gas cloud where stars are born, the magnetic field lines are roughly aligned in one direction, like the fibers in a piece of felt. But look inside, into the dense clumps that will eventually become stars, and the picture changes: there the lines are twisted every which way, like a ball of yarn after a kitten has played with it.

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.

The star GJ 436 is a dim red dwarf, and orbiting it is a Neptune-sized planet on a nearly vertical, tilted orbit. Astronomers spent 18 years taking spectra of this star to track its spots and flares. Suddenly, a rhythm emerged in the data that matched neither the star's rotation nor its 8-year activity cycle. This rhythm exactly followed the planet's orbit.

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.

A neutron star is a city the size of a metropolis squeezed into a small asteroid. Around it, plasma, a gas of charged particles, seethes, and waves ripple through it like ripples on a pond. There are three kinds of waves: Alfvén (A), ordinary (O), and extraordinary (X).

Until now, dark energy has been studied like a car engine — only by the acceleration the Universe's expansion gains.

A galaxy plunges into a dense cluster like a runner into a crowd. The oncoming gas, known as the intracluster medium, strips away its own gas, stretching it into a long, glowing tail. Astronomers call these galaxies jellyfish: they have a body and flowing tentacles of stripped material. But only in a few do new stars ignite within those tentacles.

In its first moments, the universe resembled dough that alternately rises rapidly and then pauses for a second. During these short bursts, called expansion of the universe with interruptions, even tiny magnetic fields could have grown like bubbles in well-beaten dough.

A spinning black hole acts like a cosmic generator: its rotation pumps energy into an invisible scalar cloud — a prime candidate for dark matter. A scalar field is like temperature: at every point in space it's just a single number, with no arrows or vectors. The cloud grows until it overflows.

Astronomers have been wrestling for years with the mystery of fast radio bursts — ultra-short yet incredibly powerful radio signals from distant galaxies. Some flash repeatedly, like beacons with an irregular rhythm, while others are detected only once, leaving behind nothing but questions.