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Abstract

Using a single N-body simulation we explore the formation, evolution, and spatial variation of the phase-space
spirals similar to those recently discovered in the Milky Way disk. For the first time in the literature we use
a self-consistent N-body simulation of an isolated Milky Way-type galaxy to show that the phase-space spirals
develop naturally from vertical waves driven by the buckling of the stellar bar. Such vertical oscillations trigger
the formation of various time-dependent phase-space spirals in the entire disk. The underlying physical mechanism
implies the link between in-plane and vertical motion that leads directly to phase-space structures whose amplitude
and shape are in remarkable agreement with those of the phase-space spirals observed in the Milky Way disk. In
our isolated galaxy simulation, phase-space spirals are still distinguishable at the solar neighborhood 3 Gyr after
the buckling phase. The long-lived character of the phase-space spirals generated by the bar buckling instability
cast doubts on the timing argument used so far to get back to the time of the onset of the perturbation.