1 week Ago By Amit Malewar
From boring to bursting. Supermassive black holes are challenging to observe because they can stay dormant for long periods. This was the case for the black hole in galaxy SDSS1335+0728, 300 million light-years away in Virgo.
After decades of inactivity, it suddenly became active, emitting powerful X-ray bursts . The galaxy SDSS1335+0728, which had remained stable for 20 years, began showing increased optical brightness in December 2019. This was followed by five years of fluctuations resembling active galactic nucleus (AGN) behavior.
After years of observation, researchers concluded that the sudden changes in the galaxy were likely caused by its black hole “switching on” and entering an active phase. The bright, central region of the galaxy has now been designated as an active galactic nucleus, affectionately nicknamed ‘Ansky.’ When Ansky was first observed lighting up in optical images, researchers initiated follow-up studies using NASA’s Swift X-ray space telescope.
They examined past data from the eROSITA X-ray telescope. However, no X-ray emissions were detected at that time. Since February 2024, researcher Lorena Hernández-García from Valparaíso University, Chile, has detected X-ray emissions from the reawakening black hole Ansky.
These observations revealed extreme quasiperiodic eruptions (QPEs)—brief, flaring events characterized by high fluxes, strong amplitudes, extended timescales, significant integrated energy, and a roughly 25-day superperiod. This marks the first-ever detection of such phenomena in a black hole transitioning to an active state. QPEs are thought to be caused by an object, like a star or small black hole, interacting with the accretion disc and have been linked to star destruction.
However, there’s no evidence Ansky destroyed a star. Researchers propose another explanation: the accretion disc might be made of gas drawn from the black hole’s surroundings , not a disintegrated star. The X-ray flares could result from energetic shocks caused by a small object disrupting the orbiting material as it moves through the disc repeatedly.
Ansky’s X-ray bursts are ten times longer and brighter than typical QPEs, releasing more energy and showing the longest cadence observed—about 4.5 days. These extreme eruptions challenge existing models and push scientists to rethink how such flashes are produced.
Observing Ansky in real time gives astronomers a rare chance to study black holes and their energetic events. For QPEs, researchers still lack enough data and need further observations to understand their causes. While QPEs were thought to result from small objects spiraling into larger ones, Ansky’s bursts suggest a different mechanism, possibly linked to gravitational waves that ESA’s LISA mission might detect.
X-ray observations are essential to complement gravitational wave data and uncover the mysteries of massive black holes . Journal Reference: Hernández-García, L., Chakraborty, J.
, Sánchez-Sáez, P. et al. Discovery of extreme quasi-periodic eruptions in a newly accreting massive black hole.
Nat Astron (2025). DOI: 10.1038/s41550-025-02523-9 Topics Black Hole ESA Galaxy x-ray.
