Dark Sunshine: Detecting Dark Matter through Dark Photons from the Sun

TL;DR

This paper proposes a novel method to detect dark matter by observing dark photons emitted from the Sun, which decay into detectable particles, offering a new way to explore dark matter properties with existing AMS data.

Contribution

It provides a comprehensive analysis of dark photon signals from dark matter annihilation in the Sun, including effects like Sommerfeld enhancement and magnetic fields, and suggests a new search strategy using AMS data.

Findings

Potential dark matter detection with AMS in the 1-10 TeV mass range.

Parameter space for dark photons with masses around 100 MeV and kinetic mixing from 10^{-10} to 10^{-8}.

Extension beyond current experimental bounds and complementarity to other detection methods.

Abstract

Dark matter may interact with the Standard Model through the kinetic mixing of dark photons, $A'$, with Standard Model photons. Such dark matter will accumulate in the Sun and annihilate into dark photons. The dark photons may then leave the Sun and decay into pairs of charged Standard Model particles that can be detected by the Alpha Magnetic Spectrometer. The directionality of this "dark sunshine" is distinct from all astrophysical backgrounds, providing an opportunity for unambiguous dark matter discovery by AMS. We perform a complete analysis of this scenario including Sommerfeld enhancements of dark matter annihilation and the effect of the Sun's magnetic field on the signal, and we define a set of cuts to optimize the signal probability. With the three years of data already collected, AMS may discover dark matter with mass 1 TeV $\lesssim m_X \lesssim$ 10 TeV, dark photon masses $m_{A'} \sim \mathcal O(100)$ MeV, and kinetic mixing parameters $10^{-10} \lesssim \varepsilon \lesssim 10^{-8}$. The proposed search extends beyond existing beam dump and supernova bounds, and it is complementary to direct detection, probing the same region of parameter space for elastic dark matter, but potentially far more in the case of inelastic dark matter.