Flip-flop states in X-ray binaries and changing-state AGN
: Maccarone, Thomas; Runnoe, Jessie C.; Marcel, Gregoire; Järvelä, Emilia; Buisson, Douglas; Kashyap, Unnati; Vincentelli, Federico
Publisher: CSIRO Publishing
: 2026
Publications of the Astronomical Society of Australia
: e044
: 43
: 1323-3580
: 1448-6083
DOI: https://doi.org/10.1017/pasa.2026.10176
: https://doi.org/10.1017/pasa.2026.10176
: https://research.utu.fi/converis/portal/detail/Publication/523244243
We show that the flip-flop transitions in X-ray binaries (rapid cycling between different spectral states which are sometimes seen near the global state transition) show a series of analogies to the changing state phenomena (rapid changes in the emission line properties that seem to be driven by changes in the central engine) in active galactic nuclei (AGN). Specifically, (1) the timescales for the transitions scale approximately linearly with mass and (2) both phenomena occur at a few percent of the Eddington luminosity. Because most accretion physics is expected to be scale-free, it is likely that these represent two manifestations of the same phenomena. Demonstrating this would allow the use of a much wider range of observational techniques, on a much wider range of characteristic timescales, and provide a clearer pathway towards understanding these rapid transitions than is currently available. We discuss potential means to establish the connection more firmly and to use the combination of the observational advantages of both classes of systems to develop a better understanding of the phenomenon.
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GM acknowledges financial support from the Academy of Finland grant 355672. This research was supported in part by grant NSF PHY-2309135 to the Kavli Institute for Theoretical Physics (KITP).