Millihertz oscillations near the innermost orbit of a supermassive black hole

Masterson, M; Kara, E; Panagiotou, C; Alston, WN; Chakraborty, J; Burdge, K; Ricci, C; Laha, S; Arcavi, I; Arcodia, R; Cenko, SB; Fabian, AC; Garcia, JA; Giustini, M; Ingram, A; Kosec, P; Loewenstein, M; Meyer, ET; Miniutti, G; Pinto, C; Remillard, RA; Sadaula, DR; Shuvo, OI; Trakhtenbrot, B; Wang, J

doi:10.1038/s41586-024-08385-x

Millihertz oscillations near the innermost orbit of a supermassive black hole

Lookup NU author(s): Dr Adam Ingram ORCiD

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Abstract

© The Author(s), under exclusive licence to Springer Nature Limited 2025. Recent discoveries from time-domain surveys are defying our expectations for how matter accretes onto supermassive black holes (SMBHs). The increased rate of short-timescale, repetitive events around SMBHs, including the recently discovered quasi-periodic eruptions1, 2, 3, 4–5, are garnering further interest in stellar-mass companions around SMBHs and the progenitors to millihertz-frequency gravitational-wave events. Here we report the discovery of a highly significant millihertz quasi-periodic oscillation (QPO) in an actively accreting SMBH, 1ES 1927+654, which underwent a major optical, ultraviolet and X-ray outburst beginning in 20186,7. The QPO was detected in 2022 with a roughly 18-minute period, corresponding to coherent motion on a scale of less than 10 gravitational radii, much closer to the SMBH than typical quasi-periodic eruptions. The period decreased to 7.1 minutes over 2 years with a decelerating period evolution (P¨ greater than zero). To our knowledge, this evolution has never been seen in SMBH QPOs or high-frequency QPOs in stellar-mass black holes. Models invoking orbital decay of a stellar-mass companion struggle to explain the period evolution without stable mass transfer to offset angular-momentum losses, and the lack of a direct analogue to stellar-mass black-hole QPOs means that many instability models cannot explain all of the observed properties of the QPO in 1ES 1927+654. Future X-ray monitoring will test these models, and if it is a stellar-mass orbiter, the Laser Interferometer Space Antenna (LISA) should detect its low-frequency gravitational-wave emission.

Publication metadata

Author(s): Masterson M, Kara E, Panagiotou C, Alston WN, Chakraborty J, Burdge K, Ricci C, Laha S, Arcavi I, Arcodia R, Cenko SB, Fabian AC, Garcia JA, Giustini M, Ingram A, Kosec P, Loewenstein M, Meyer ET, Miniutti G, Pinto C, Remillard RA, Sadaula DR, Shuvo OI, Trakhtenbrot B, Wang J

Publication type: Article

Publication status: Published

Journal: Nature

Year: 2025

Volume: 638

Pages: 370-375

Print publication date: 13/02/2025

Online publication date: 05/02/2025

Acceptance date: 11/11/2024

ISSN (print): 0028-0836

ISSN (electronic): 1476-4687

Publisher: Springer Nature