Flip-flop states in X-ray binaries and changing-state AGN

TL;DR

This paper explores the analogy between flip-flop state transitions in X-ray binaries and changing-state phenomena in AGN, suggesting they are manifestations of the same underlying accretion physics across different scales.

Contribution

It proposes that the observed phenomena in X-ray binaries and AGN are scale-invariant manifestations of the same accretion processes, enabling cross-system insights.

Findings

Transition timescales scale linearly with mass

Both phenomena occur at a few percent of Eddington luminosity

Potential for unified understanding of accretion physics

Abstract

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 toward 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.