He Gao

The Einstein Probe space telescope detected a celestial storm: after a short (0.4-second) gamma-ray burst — a cosmic lightning bolt — came a long roll of X-ray thunder. It lasted nearly 10 minutes. This is the first direct proof that such explosions leave a lingering X-ray afterglow.

Inside the receiver of a telescope aimed at the oldest glow in the universe sits a tiny thermometer chip. It's so sensitive that the heat from a single photon can warm it noticeably. But to hear that whisper of heat, you need a middleman — an amplifier that doesn't add its own noise.

An X-ray photon hits the detector like a pebble dropping into still water. The water is a thin film of aluminum and manganese, cooled to near absolute zero. The impact sends a heat wave rippling across the film, and by measuring its height, you can tell how much energy the photon carried.

A stack of identical pancakes on a plate is just a stack. But if you arrange them with a certain order, something new suddenly appears: for example, a pattern that was not visible in each pancake individually. Physicists have performed a similar trick with thin layers of materials.

A gamma-ray burst is like a shot from a cosmic cannon: a brief but dazzling flash that outshines an entire galaxy for a few seconds. But when observed in the hardest gamma-ray band (photons with energies above a gigaelectronvolt), the signal often gets lost in the noise, like a whisper in a noisy hall.

In the dense family of old stars that astronomers call the cluster NGC 6791, a lonely radio beacon has been spotted — the pulsar PSR J1922+3745. Such objects are born when a massive star explodes and its core collapses into a tiny sphere the size of a city, which spins and emits radio waves like a rotating lighthouse beam.

In a distant galaxy, at a distance that light takes 11 billion years to cross, something flashed. The Einstein Probe X-ray telescope caught a brief, needle-prick-like burst: it lasted only a few dozen seconds.

Imagine a long corridor with an uneven floor: bumps here, pits there. If you roll a toy car along it, it will get stuck in the deepest pit, not where you gave it a push. That's roughly how sound behaves in a phononic crystal — a material made of periodically arranged elements that controls the propagation of elastic waves.

Black holes come in lightweights, born from dying stars, and supermassive ones at galactic cores. The missing intermediate link had been hiding. Fast radio bursts, cosmic signals lasting milliseconds but carrying the energy of days of sunlight, helped crack the case. Think of these bursts as cries from the depths of the universe.

Since their discovery in 2007, fast radio bursts (FRBs) have teased astrophysicists with their elusive nature. These millisecond signals arrive from distant galaxies and carry colossal energy: for an instant, they radiate as much as the Sun does in a month.

A massive star ends its life in a spectacular collapse: the core compresses into a neutron star or a black hole, while the outer layers fly off in a dazzling supernova.