Physical origin of Ansky’s secular period increase

Determine the physical origin of the persistent recurrence-period increase observed in the QPE source Ansky, which has a positive period derivative inconsistent with orbital decay from purely dissipative processes.

Background

The paper describes Ansky as a QPE source whose recurrence period increased from approximately 4.5 to 10 days and later reached approximately 14 days, with a measured positive period derivative. This behavior contrasts with the period decrease expected from gas drag and gravitational-wave emission in recurrent disk-crossing scenarios. Although the proposed satellite-black-hole–disk-transit model can reproduce Ansky’s flare duration and delayed UV counterpart for suitable instantaneous parameters, the broader physical origin of Ansky’s secular timing evolution remains unresolved.

References

Its physical origin remains unresolved.

— Quasi-periodic Eruptions from Recurrent Satellite Black Hole Transits through Magnetized Galactic Nucleus Accretion Disks  (2608.19796 - Wang et al., 20 Aug 2026) in Section 1, Introduction

This is in fact comparable to the observed $\dot{P}\approx(1.7\pm0.02)\times10{-2}$ d d${-1}$ \citep{Chakraborty26a}; however, it is unclear whether the required anisotropy can be produced, motivating further study of the collision dynamics (see also \citealt{Linial24a} for further discussion).

— Relativistic outflows power a quasi-periodic eruption: constraints on energetics, mass loss, and emission mechanisms  (2608.28507 - Chakraborty et al., 28 Aug 2026) in Section 3.1, “Constraints on energetics, long-term evolution, and QPE models”