Accurate calculations of the WIMP halo around the Sun and prospects for its gamma-ray detection

TL;DR

This study uses detailed simulations to estimate the gamma-ray flux from WIMP annihilations around the Sun, concluding it is negligible and undetectable with current technology.

Contribution

It provides a comprehensive, simulation-based analysis of the WIMP halo around the Sun, improving upon previous simplified estimates.

Findings

Gamma-ray flux from WIMP annihilation around the Sun is negligible.

No current or planned detectors can detect this gamma-ray flux.

Detailed modeling shows the flux is much lower than earlier estimates.

Abstract

Galactic weakly interacting massive particles (WIMPs) may scatter off solar nuclei to orbits gravitationally bound to the Sun. Once bound, the WIMPs continue to lose energy by repeated scatters in the Sun, eventually leading to complete entrapment in the solar interior. While the density of the bound population is highest at the center of the Sun, the only observable signature of WIMP annihilations inside the Sun is neutrinos. It has been previously suggested that although the density of WIMPs just outside the Sun is lower than deep inside, gamma rays from WIMP annihilation just outside the surface of the Sun, in the so called WIMP halo around the Sun, may be more easily detected. We here revisit this problem using detailed Monte Carlo simulations and detailed composition and structure information about the Sun to estimate the size of the gamma-ray flux. Compared to earlier simpler estimates, we find that the gamma-ray flux from WIMP annihilations in the solar WIMP halo would be negligible; no current or planned detectors would be able to detect this flux.