Letter to the Editor

Discovery of crested quasi-periodic eruptions following the most luminous SRG/eROSITA tidal disruption event

¹ Max-Planck-Institut für extraterrestrische Physik Gießenbachstraße 1 85748 Garching, Germany
² Excellence Cluster ORIGINS Boltzmannsstraße 2 85748 Garching, Germany
³ School of Physics and Astronomy, Tel Aviv University Tel Aviv 69978, Israel
⁴ Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology Cambridge MA 02139, USA
⁵ Centro de Astrobiologia (CAB), CSIC-INTA, Camino Bajo del Castillo s/n ESAC 28692 Villanueva de la Cañada Madrid, Spain
⁶ European Southern Observatory Karl-Schwarzschild-Strasse 2 85748 Garching bei München, Germany
⁷ Centre for Astrophysics Research, University of Hertfordshire College Lane Hatfield AL10 9AB, UK

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 24 November 2025
Accepted: 12 January 2026

Abstract

We report the discovery of complex flaring activity from the galactic nucleus hosting the five-year-old tidal disruption event eRASSt J234402.9−352640 (J2344). With Einstein Probe and XMM-Newton observations, we detected highly structured soft X-ray variability. Through temporal decomposition of the XMM-Newton light curve and time-resolved spectral analysis, we identified broad, thermal flares recurring every ∼12 hours and lasting ∼2 hours, consistent with quasi-periodic eruptions (QPEs). Remarkably, these QPEs are accompanied by an unprecedented crest of hotter shorter flares, each lasting between 5 and 30 minutes. These flares are predominantly found in the rising phases of the QPEs, although they also appear throughout the quiescence. These findings establish J2344 as a new member of the QPE emitter population and uncover a previously unobserved phenomenology that challenges current models of QPEs. In this letter we present the phenomenological properties of this unique source and discuss possible interpretations within the framework of extreme mass ratio inspirals.