Photon frequency diffusion process

TL;DR

This paper introduces a stochastic model for photon frequency diffusion, deriving a nonlinear Markov process that captures nonequilibrium effects and fluctuations around the Kompaneets equation, with implications for Planck Law modifications.

Contribution

It develops a novel stochastic multi-photon dynamics framework on reciprocal space, extending the classical models to include nonequilibrium effects and stimulated emission.

Findings

Derivation of a nonlinear Markov process for photon frequency diffusion.

Connection to fluctuations around the Kompaneets equation.

Potential to explore modifications of the Planck Law at low frequencies.

Abstract

We introduce a stochastic multi-photon dynamics on reciprocal space. Assuming isotropy, we derive the diffusion limit for a tagged photon to be a nonlinear Markov process on frequency. The nonlinearity stems from the stimulated emission. In the case of Compton scattering with thermal electrons, the limiting process describes the dynamical fluctuations around the Kompaneets equation. More generally, we construct a photon frequency diffusion process which enables to include nonequilibrium effects. Modifications of the Planck Law may thus be explored, where we focus on the low-frequency regime.