Orbital Dynamics of the Solar Basin

TL;DR

This paper investigates the long-term behavior and density modulation of particles in the solar basin, revealing a lifetime of about 1.2 billion years and seasonal density variations, with implications for dark matter detection.

Contribution

It provides the first detailed analysis of the solar basin dynamics using combined analytic and numerical methods, including lifetime estimates and modulation patterns.

Findings

Effective lifetime of solar basin at Earth: 1.20 Gyr

Annual and semi-annual density modulations detected

Implications for dark matter detection and gravitational capture

Abstract

We study the dynamics of the solar basin -- the accumulated population of weakly-interacting particles on bound orbits in the Solar System. We focus on particles starting off on Sun-crossing orbits, corresponding to initial conditions of production inside the Sun, and investigate their evolution over the age of the Solar System. A combination of analytic methods, secular perturbation theory, and direct numerical integration of orbits sheds light on the long- and short-term evolution of a population of test particles orbiting the Sun and perturbed by the planets. Our main results are that the effective lifetime of a solar basin at Earth's location is $\tau_{\rm eff} = 1.20\pm 0.09 \,\mathrm{Gyr}$, and that there is annual (semi-annual) modulation of the basin density with known phase and amplitude at the fractional level of 6.5% (2.2%). These results have important implications for direct detection searches of solar basin particles, and the strong temporal modulation signature yields a robust discovery channel. Our simulations can also be interpreted in the context of gravitational capture of dark matter in the Solar System, with consequences for any dark-matter phenomenon that may occur below the local escape velocity.