Testing EMRI Models for Quasi-periodic Eruptions with 3.5 yr of Monitoring eRO-QPE1

Journal article

Quasi-periodic eruptions (QPEs) are luminous X-ray outbursts recurring on hour timescales, observed from the nuclei of a growing handful of nearby low-mass galaxies. Their physical origin is still debated, and usually modeled as (a) accretion disk instabilities or (b) interaction of a supermassive black hole (SMBH) with a lower mass companion in an extreme mass-ratio inspiral (EMRI). EMRI models can be tested with several predictions related to the short- and long-term behavior of QPEs. In this study, we report on the ongoing 3.5 yr NICER and XMM-Newton monitoring campaign of eRO-QPE1, which is known to exhibit erratic QPEs that have been challenging for the simplest EMRI models to explain. We report (1) complex, non-monotonic evolution in the long-term trends of QPE energy output and inferred emitting area; (2) the disappearance of the QPEs (within NICER detectability) in 2023 October, and then the reappearance by 2024 January at a luminosity of ∼100× fainter (and temperature of ∼3× cooler) than the initial discovery; (3) radio non-detections with MeerKAT and Very Large Array observations partly contemporaneous with our NICER campaign (though not during outbursts); and (4) the presence of a possible ∼6 day modulation of the QPE timing residuals, which aligns with the expected nodal precession timescale of the underlying accretion disk. Our results tentatively support EMRI-disk collision models powering the QPEs, and we demonstrate that the timing modulation of QPEs may be used to jointly constrain the SMBH spin and disk density profile

Authors: Chakraborty, J; Arcodia, R; Kara, E; Miniutti, G; Giustini, M

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Astronomical Society
• Journal: The Astrophysical Journal
• Volume: 965
• Issue: 1
• Pages: 12-12
• Publication date: 2024-04-01
• DOI: 10.3847/1538-4357/ad2941
• EISSN: 1538-4357
• ISSN: 0004-637X
• Language: English
• Keywords: Geology; Environmental science; Seismology