AI Insight
Astronomers using the eROSITA space telescope have identified HE 1237−2252 as a "changing-look" Seyfert galaxy, in which the central supermassive black hole appeared to dramatically reduce and then resume its activity. The galaxy's X-ray emission dimmed by a factor of 17 within just 18 months before recovering, making it one of the more extreme examples of rapid AGN variability observed. This behavior suggests that accretion processes around the black hole can change on unexpectedly short timescales, challenging existing models of AGN activity.
Why it matters
Understanding how and why supermassive black holes can switch on and off so rapidly provides critical constraints on accretion disk physics and the co-evolution of black holes with their host galaxies. This has broader implications for our understanding of galaxy formation and the feedback mechanisms that regulate star formation.
Astronomers have tracked a dramatic “changing-look” active galactic nucleus (AGN) whose central supermassive black hole appeared to switch off and then rapidly reignite. The galaxy, HE 1237−2252, dimmed in X-rays by a factor of 17 within just 18 months before recovering again. The paper outlining its analysis was uploaded to the arXiv preprint server on May 8.