Spinning dust radiation: a review of the theory

TL;DR

This review comprehensively discusses the theoretical modeling of electric dipole radiation emitted by spinning dust grains, highlighting the physical processes, computational methods, and current uncertainties affecting predictions.

Contribution

It synthesizes existing theories on dust grain rotation and radiation, emphasizing the impact of grain properties and uncertainties on modeling accuracy.

Findings

Theoretical models depend heavily on grain properties like abundance and dipole moments.

Rotational excitation and damping mechanisms are well-characterized but uncertain due to grain diversity.

Predictions are limited mainly by uncertainties in grain physical characteristics.

Abstract

This article reviews the current status of theoretical modeling of electric dipole radiation from spinning dust grains. The fundamentally simple problem of dust grain rotation appeals to a rich set of concepts of classical and quantum physics, owing the the diversity of processes involved. Rotational excitation and damping rates through various mechanisms are discussed, as well as methods of computing the grain angular momentum distribution function. Assumptions on grain properties are reviewed. The robustness of theoretical predictions now seems mostly limited by the uncertainties regarding the grains themselves, namely their abundance, dipole moments, size and shape distribution.