When a star passes too close to a supermassive black hole, the enormous tidal forces can tear it apart, creating a temporary disk of glowing gas. Such tidal disruption events offer a fleeting opportunity to study otherwise invisible black holes. In recent years, X-ray observatories have revealed that some of these events display repeating bursts of X-rays — known as quasi-periodic eruptions (QPEs). These intense and regular pulses occur only in a handful of known sources and remain an open mystery in high-energy astrophysics. They have quasi-periodicities ranging from a few hours to a few days. In a new study led by MPE PhD student Pietro Baldini, astronomers report that J2344 exhibits QPE-like eruptions— but with unprecedented behaviour uncovered thanks to follow-up observations with the Einstein Probe and XMM-Newton satellites. “Quasi-periodic eruptions are extremely rare, so I was already excited when I saw the Einstein Probe light curve,” says Pietro Baldini. “But when the XMM-Newton data came in, my jaw dropped: not only had we discovered a new QPE source, but its behaviour was completely unprecedented.”
Zoom on the features of the XMM-Newton lightcurve of J2344: A crest of narrow flares can be distinctively observed over the broader modulations (the QPEs)
Astronomers have uncovered a rare and unexpectedly complex pattern of X-ray eruptions in the source eRASSt J2344, the most luminous tidal disruption event discovered by SRG/eROSITA. Follow-up observations with Einstein Probe and XMM-Newton reveal powerful outbursts repeating every twelve hours - the hallmark of quasi-periodic eruptions (QPEs) - but with an unprecedented addition: shorter, hotter mini-flares embedded within them. This layered behavior challenges current models of how matter behaves in the closest regions around supermassive black holes.
Cosmic ECG of J2344
Animation of the X-ray lightcurve of J2344. The sequence is sped up by a factor of 10,000, revealing rhythmic eruptions and brief, intense mini-flares appearing at the beginning, middle, and end of the lightcurve – like a cosmic electrocardiogram.
The observations revealed a sequence of main X-ray eruptions lasting about two hours and recurring every twelve hours, a typical pattern for known QPEs. However, J2344 also produced a series of much shorter and hotter flares, lasting only a few minutes — a feature never observed before in such systems. The leading explanation for QPEs involves a smaller object, such as a star, orbiting the supermassive black hole and interacting periodically with its accretion disk. While this model explains the regular main eruptions, it cannot account for the additional rapid flares seen in J2344. Their presence indicates that the physics of matter near black holes may be more complex than previously thought. To better understand the mechanisms at work, the team has been awarded additional observation time to monitor J2344 over longer timescales and explore how the two types of flares are connected.
Since its launch in January 2024, the Einstein Probe (EP) has been continuously surveying the variable X-ray sky. Its wide-field optics and high-cadence observations, together with its sensitive follow-up X-ray telescopes. make it uniquely capable of capturing rare and transient events such as QPEs. “Since launch, Einstein Probe has opened an entirely new discovery space in X-ray astronomy,” says Arne Rau (MPE). “This result is just a first glimpse of the kind of rare and unexpected phenomena we expect to find, and we are very excited about what comes next.” As Einstein Probe continues its mission, astronomers expect to uncover more of these enigmatic systems, providing fresh insights into the dynamic behaviour of supermassive black holes — and the extreme environments around them.
The observations revealed a sequence of main X-ray eruptions lasting about two hours and recurring every twelve hours, a typical pattern for known QPEs. However, J2344 also produced a series of much shorter and hotter flares, lasting only a few minutes — a feature never observed before in such systems. The leading explanation for QPEs involves a smaller object, such as a star, orbiting the supermassive black hole and interacting periodically with its accretion disk. While this model explains the regular main eruptions, it cannot account for the additional rapid flares seen in J2344. Their presence indicates that the physics of matter near black holes may be more complex than previously thought. To better understand the mechanisms at work, the team has been awarded additional observation time to monitor J2344 over longer timescales and explore how the two types of flares are connected.
Since its launch in January 2024, the Einstein Probe (EP) has been continuously surveying the variable X-ray sky. Its wide-field optics and high-cadence observations, together with its sensitive follow-up X-ray telescopes. make it uniquely capable of capturing rare and transient events such as QPEs. “Since launch, Einstein Probe has opened an entirely new discovery space in X-ray astronomy,” says Arne Rau (MPE). “This result is just a first glimpse of the kind of rare and unexpected phenomena we expect to find, and we are very excited about what comes next.” As Einstein Probe continues its mission, astronomers expect to uncover more of these enigmatic systems, providing fresh insights into the dynamic behaviour of supermassive black holes — and the extreme environments around them.
Contacts:
Pietro Baldini
PhD-student
Tel: +49 89 30000-3269
Email: baldini@mpe.mpg.de
Arne Rau
scientist
Tel: +49 89 30000-3851
Fax: +49 89 30000-3569
Email: arau@mpe.mpg.de
Kirpal Nandra
managing director
Tel: +49 89 30000-3401
Fax: +49 89 30000-3569
knandra@mpe.mpg.de
Publication
P. Baldini, A. Rau, A. Merloni, B. Trakhtenbrot, R. Arcodia, M. Giustini, G. Miniutti, S. J. Brennan, M. Freyberg, P. Sánchez-Sáez, I. Grotova, Z. Liu, T. Lian, K. Nandra
Discovery of crested quasi-periodic eruptions following the most luminous SRG/eROSITA tidal disruption eventhttps://doi.org/10.1051/0004-6361/202558241
