Dark Photons in the Solar Basin

TL;DR

This paper explores how dark photons produced in the Sun can accumulate in gravitationally bound orbits, creating a 'Solar basin' that can be detected by dark matter experiments, offering new ways to probe dark photon properties.

Contribution

It introduces the concept of a Solar basin of dark photons and demonstrates its potential to reveal new parameter space in dark photon searches, independent of dark matter composition.

Findings

Current experiments already constrain new parameter space.

A Solar basin could explain excess events in XENON1T.

Future experiments could detect sub-eV dark photons at very low couplings.

Abstract

Production of dark photons inside the Sun forms the basis for the most sensitive probes of such particles over a wide mass range. A small fraction of dark photons is emitted into gravitationally bound orbits, building up a "Solar basin" population that survives for astrophysically long times. We show that this population could lead to signals in existing and proposed dark matter detection experiments, opening up significant new parameter space independent of whether dark photons make up the dark matter. Even with conservative assumptions, results from current dark matter experiments already constrain new parameter space; with fiducial assumptions, a Solar basin population of dark photons could be responsible for excess events seen in XENON1T. Future low-threshold experiments could be sensitive to these Solar-System-bound dark photons down to sub-eV masses, at couplings orders of magnitude below current constraints.