X-ray quasi periodic eruptions (QPEs) are among the most fascinating cosmic phenomena discovered in the past years, and perhaps the most unexpected of all.
Twelve hours of observations with the ESA telescope XMM-Newton have opened a completely new avenue to study the complex dynamics of the nuclei of galaxies, where supermassive black holes interact with the crowded nuclear environment that includes stars, stellar remnants, nuclear star clusters, tidal disruption events of stars, gas clouds, planets.
In just a few years, QPEs have become the new frontier of astrophysical studies of cosmic black holes.
What are QPEs? They are intense bursts of X-ray radiation associated with massive black holes in galactic nuclei, that appear to recur quasi-periodically, on time scales between few hours and few days.
Discovered at the end of 2018 in the nucleus of the galaxy GSN 069, QPEs have now been observed in a dozen of galaxies. The physical explanation for QPEs is not yet established, but the most likely scenarios appear to be extreme mass ratio inspirals and accretion flow instabilities. Massive observational campaigns with the major existing facilities are ongoing, both to investigate the known sources in detail, and to discover more QPE sources.
Scientific literature on QPEs, observational articles:
GSN 069: “Nine-hour X-ray quasi-periodic eruptions from a low-mass black hole galactic nucleus” — Miniutti et al. 2019, Nature 573, 381, arXiv: https://arxiv.org/abs/1909.04693
RX J1301.9+2747: “X-ray quasi-periodic eruptions from the galactic nucleus of RX J1301.9+2747” — Giustini et al. 2020, A&A 636, 2, arXiv: https://arxiv.org/abs/2002.08967
XMMSL J0249: “Possible X-Ray Quasi-periodic Eruptions in a Tidal Disruption Event Candidate” — Chakraborty et al. 2021, ApJ 921, 40, arXiv: https://arxiv.org/abs/2110.10786
eRO-QPE1 and eRO-QPE2: “X-ray quasi-periodic eruptions from two previously quiescent galaxies” — Arcodia et al. 2021, Nature 592, 704, arXiv: https://arxiv.org/abs/2104.13388
AT2019vcb (Tormund): “Tormund’s return: Hints of quasi-periodic eruption features from a recent optical tidal disruption event” — Quintin et al. 2023, A&A 675, 152, arXiv: https://arxiv.org/abs/2306.00438
eRO-QPE3 and eRO-QPE4: “The more the merrier: SRG/eROSITA discovers two further galaxies showing X-ray quasi-periodic eruptions” — Arcodia et al. 2024, A&A 684, 64, arXiv: https://arxiv.org/abs/2401.17275
AT2019qiz: “Quasi-periodic X-ray eruptions years after a nearby tidal disruption event” — Nicholl et al. 2024, Nature 634, 804, arXiv: https://arxiv.org/abs/2409.02181
AT2022upj: “Discovery of Quasiperiodic Eruptions in the Tidal Disruption Event and Extreme Coronal Line Emitter AT2022upj: Implications for the QPE/TDE Fraction and a Connection to ECLEs” — Chakraborty et al. 2025, ApJ 983, 39, arXiv: https://arxiv.org/abs/2503.19013
SDSS1335+0728 (Ansky): “Discovery of extreme quasi-periodic eruptions in a newly accreting massive black hole” — Hernández-García et al. 2025, Nature Astronomy 9, 895, arXiv: https://arxiv.org/abs/2504.07169
eRO-QPE5: “SRG/eROSITA No. 5: Discovery of Quasiperiodic Eruptions Every ∼3.7 days from a Galaxy at z > 0.1” — Arcodia et al. 2025, ApJ 989, 13, arXiv: https://arxiv.org/abs/2506.17138
Some scientific talks about QPEs:
💻 “X-ray quasi-periodic eruptions (QPEs)” — pdf of the slides presented by Giovanni Miniutti at the “X-ray Astronomy 2019” conference, held in Bologna (Italy) in September 2019.
💻 “Nine hour X-ray Quasi-Periodic Eruptions (QPEs) from the nucleus of the Galaxy GSN 069” — pdf of the slides presented by Giovanni Miniutti at the “XMM-Newton 20th anniversary” event held at the European Space Astronomy Centre (ESAC, Spain) in December 2019.
Video of the talk: here.
💻 “The discovery of X-ray quasi-periodic eruptions” (video) — seminar given by myself at the Centro de Astrobiologia, July 2020.
💻 “Unexpected signals in the X-ray sky: quasi-periodic eruptions from galactic nuclei” (video) — seminar given by myself for the Athena X-ray Advances: ASST & ACO Science Webinars, March 2022
💻 “What’s new on the eROSITAS QPEs” (video) — IAS seminar by Riccardo Arcodia, June 2023
💻 “X-ray quasi-periodic eruptions (QPEs)” (video) –talk by Joheen Chakraborty at the “Anticipating the Rising Tide of Tidal Disruption Events: Theory and Observation” conference at the Kavli Institute for Theoretical Physics (KITP), April 2024
💻 “QPEs and their connection with TDEs: where do we stand” (video) –talk by Riccardo Arcodia at the “Anticipating the Rising Tide of Tidal Disruption Events: Theory and Observation” conference at the Kavli Institute for Theoretical Physics (KITP), April 2024
Margherita Giustini 