Black Hole Throws Off Its Rhythm ⚡ экспресс
For the first time, the period derivative of a quasi-periodic eruption (QPE) has been directly measured for source ZTF19acnskyy/Ansky. The period is found to be smoothly increasing at a rate of (1.7±0.02)×10⁻² days per day. This positive trend is unexpected for models where a star orbits a supermassive black hole in an extreme mass-ratio inspiral (EMRI) — typically the period decreases. Various mechanisms were analyzed: stable mass transfer induced by impulsive mass loss; tidal velocity kicks; apparent period changes from general relativistic precession or light delays in a hierarchical binary; variations in the thermal/viscous instability model of the disk. None of the hypotheses fully describe the data, pointing to the need for new physical interpretations of positive period derivatives in QPEs.
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. Each successive beat lags more than the previous one: over a day, the gap grows by almost half an hour. It's as if the heart, instead of racing under stress, were slowing to a halt.
Nobody yet knows why this rhythm is slowing. Perhaps we're missing some fundamental process — for instance, an unknown way of losing energy.
🎯 Each flare lasts several hours, while the intervals between them can span months. The change in tempo has been measured with jeweler's precision: 0.017 days per day — roughly 24 minutes of daily lag.