Ying Qin

Light fades like a campfire when you stop adding wood. Gamma-ray bursts, the brightest explosions in the Universe, have their own rhythm of fading. Astronomers took 85 such bursts caught by the Swift satellite and looked at how fast their brightness drops. Inside a burst hides a black hole that greedily sucks in matter.

Astrophysicists have conducted a census of invisible objects that betray their presence only through the trembling of space. They studied the fresh catalog GWTC-4 — a list of dozens of black hole mergers recorded by the gravitational wave detectors LIGO, Virgo, and KAGRA.

Gravitational-wave detectors picked up a strange burst — the signal GW241011. Two black holes merged, but the pair looked unusual: one hole was about three times lighter than the other, and the system as a whole was spinning rapidly. Such a combination is a rare guest in the catalogs.