Supermassive Black Hole 'Ansky' Defies Theory with Slowing X-Ray Bursts
Astronomers are puzzled by the unexpected behavior of ZTF19acnskyy, nicknamed 'Ansky,' a supermassive black hole located 300 million light-years away. After awakening in 2019, Ansky began exhibiting quasi-periodic X-ray eruptions in 2024. Standard theoretical models predict that the time interval between such bursts should decrease as an orbiting object spirals closer to the black hole. However, recent analysis by Joheen Chakraborty and collaborators reveals the opposite trend. Data collected from January 2025 to January 2026 using the Neil Gehrels Swift Observatory, XMM-Newton, and NICER shows the interval between bursts increasing smoothly from 9.9 to 13.5 days, while peak luminosity remained constant. This contradicts existing explanations involving stellar mass transfer, partial disruption, relativistic precession, or binary black hole reflex motion. The study, published in 2026, highlights a significant gap in current astrophysical understanding of accretion disk dynamics and quasi-periodic eruptions, suggesting that new physical mechanisms or instabilities within the accretion disk may be responsible for this anomalous slowdown.
Wire timeline
Supermassive Black Hole 'Ansky' Defies Theory with Slowing X-Ray Bursts
Astronomers are puzzled by the unexpected behavior of ZTF19acnskyy, nicknamed 'Ansky,' a supermassive black hole located 300 million light-years away. After awakening in 2019, Ansky began exhibiting quasi-periodic X-ray eruptions in 2024. Standard theoretical models predict that the time interval between such bursts should decrease as an orbiting object spirals closer to the black hole. However, recent analysis by Joheen Chakraborty and collaborators reveals the opposite trend. Data collected from January 2025 to January 2026 using the Neil Gehrels Swift Observatory, XMM-Newton, and NICER shows the interval between bursts increasing smoothly from 9.9 to 13.5 days, while peak luminosity remained constant. This contradicts existing explanations involving stellar mass transfer, partial disruption, relativistic precession, or binary black hole reflex motion. The study, published in 2026, highlights a significant gap in current astrophysical understanding of accretion disk dynamics and quasi-periodic eruptions, suggesting that new physical mechanisms or instabilities within the accretion disk may be responsible for this anomalous slowdown.
Sky & Telescope