Inferring Time-Dependent Distribution Functions from Kinematic Snapshots [GA]

http://arxiv.org/abs/2102.03519


We propose a method for constructing the time-dependent phase space distribution function (DF) of a collisionless system from an isolated kinematic snapshot. In general, the problem of mapping a single snapshot to a time-dependent function is intractable. Here we assume a finite series representation of the DF, constructed from the spectrum of the system’s Koopman operator. This reduces the original problem to one of mapping a kinematic snapshot to a discrete spectrum rather than to a time-dependent function. We implement this mapping with a convolutional neural network (CNN). The method is demonstrated on two example models: the quantum simple harmonic oscillator, and a self-gravitating isothermal plane. The latter system exhibits phase space spiral structure similar to that observed in Gaia Data Release 2.

Read this paper on arXiv…

K. Darling and L. Widrow
Tue, 9 Feb 21
78/87

Comments: 13 pages, 11 figures