Erin Kara

About 25,000 light-years from Earth, in the constellation Sagittarius, a dense veil wraps around the neutron star GX 13+1. It scatters X-ray photons the way fog scatters streetlight, and for a long time it hid the source's true power from astronomers.

For seven hours straight, a space gamma-ray telescope registered flares that refused to end. That is how the story of GRB 250702B began: the longest gamma-ray burst ever observed. Typical bursts last seconds, rarely minutes. This one stretched to 25,000 seconds, beating the previous record by a factor of two.

One night in 2008, something in the core of the distant galaxy J1047+5907 flared sharply in X-rays. That's how the neighborhood of a supermassive black hole sometimes behaves: a scorching cloud of gas above it suddenly blasts out a powerful stream of light. The black hole itself emits nothing, but its surroundings can light up like a neon sign.

Astronomers are monitoring X-ray flares from the vicinity of a black hole at the center of a galaxy. These flares repeat with a certain rhythm, like heartbeats. Normally, as a star approaches a black hole, the rhythm speeds up — just as a pulse quickens when running. But at the black hole 'Ansky,' the rhythm is slowing down.

At the heart of galaxy 1ES 1927+654, a black hole behaves like a lighthouse with a faulty mechanism. Every six and a half minutes, it releases a burst of X-ray light, a rhythm astronomers have been tracking since 2022. At first, the beacon's tempo wandered — speeding up and slowing down, with intervals ranging from one beat every eighteen minutes to one every seven.

A lighthouse that changes the color of each flash in time with its rotation: that's one way to describe what astronomers saw when they pointed the latest X-ray telescope, XRISM, at the pulsar Hercules X-1. This object is a neutron star pulling matter from a companion ordinary star.

The Perseus galaxy cluster is a giant metropolis of thousands of star islands, bathed in an invisible ocean of scorching gas. Like urban smog, this gas preserves traces of all the chemical factories that have operated in galaxies for billions of years: supernova explosions that scatter freshly forged atoms across the surroundings.

Active galactic nuclei (AGN) are the universe’s powerhouses: their X-ray coronae blaze millions of times hotter than stellar atmospheres. But what strikes the spark? A ten-day X-ray campaign by the XRISM and XMM-Newton satellites, aimed at NGC 3783, provided the answer: it’s actual thunderstorms.

For years, silence reigned in the heart of galaxy 1ES 1927+654: the accreting gas merely whispered in X-rays, leaking slow winds. But in 2022–2025, the picture changed dramatically. Spectra taken by XMM-Newton and Swift lit up with emission lines — a narrow peak at 0.56 keV, likely from OVII oxygen, a broader feature near 1 keV, and a powerful iron band in the 6–7 keV region.