2020RAA....20...17Z

A 200-second X-ray quasi-periodicity in the 2 - 8 keV band from Swift J1644+57 was found by Reis et al. From the onset time of quasi-periodic oscillation (QPO), we show that Swift J1644+57 is a plunging event. This QPO may be related to discrete clumps from the accretion disk falling into a supermassive black hole, then the outflow in the jet may be also discontinuous. We estimate the lifetime of clumps to be about several hundreds seconds and the fraction of clumpy ejecta to be about 30% from the QPO. The other possible model involves the interface between the inflow and jet magnetosphere in the magnetically choked accretion flow. Theory and numerical simulations indicate that a magnetic Rayleigh-Taylor and Kelvin-Helmholtz unstable magnetospheric interface can produce a jet-disk QPO mechanism. This event may be the first evidence of jet-disk QPO. From observations, the two models are comparable.