Dark Solar Wind

TL;DR

This paper explores how strongly self-interacting dark sector particles emitted by the Sun can form a relativistic fluid wind with significantly higher density and lower energy per particle, leading to new experimental signatures.

Contribution

It introduces a model where dark sector particles self-thermalize and form a relativistic outflow, revealing novel signatures and motivating broader experimental searches.

Findings

Dark sector particles can self-thermalize and accelerate to relativistic speeds.

The resulting dark wind has at least 1000 times higher density than non-interacting models.

The model predicts distinctive experimental signatures for dark sector detection.

Abstract

We study the solar emission of light dark sector particles that self-interact strongly enough to self-thermalize. The resulting outflow behaves like a fluid which accelerates under its own thermal pressure to highly relativistic bulk velocities in the solar system. Compared to the ordinary non-interacting scenario, the local outflow has at least $\sim 10^3$ higher number density and correspondingly at least $\sim 10^3$ lower average energy per particle. We show how this generic phenomenon arises in a dark sector comprised of millicharged particles strongly self-interacting via a dark photon. The millicharged plasma wind emerging in this model has novel yet predictive signatures that encourages new experimental directions. This phenomenon demonstrates how a small step away from the simplest models can lead to radically different outcomes and thus motivates a broader search for dark sector particles.