The complex time and energy evolution of quasi-periodic eruptions in eRO-QPE1

Vol. 662
4. Extragalactic astronomy

The complex time and energy evolution of quasi-periodic eruptions in eRO-QPE1

by R. Arcodia, G. Miniutti, G. Ponti 2022, A&A, 662, A49 alt

Quasi-periodic eruptions (QPEs) are a recent and puzzling recurrent phenomenon that occur in the nuclei of low-mass galaxies. They consist of bright X-ray bursts that last for about half an hour and repeat every several hours. The origin of these QPEs is still unknown, and several models have been proposed. In this paper, Arcodia and coauthors, investigating the shape of these QPEs, find isolated bursts as well as bursts with a structure made by the superpositions of events. This is the first time that complex shapes have been detected. In addition, the energy spectrum of the QPEs (either simple or complex) changes with time, with the decay of each eruption being softer than its rise. No explanations for either of these new observational instances have been found yet. The mystery deepens.