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Asymmetric dark matter and the Sun

Mads T. Frandsen, Subir Sarkar

TL;DR

The paper investigates whether asymmetric dark matter (ADM) with self-interactions can accumulate in the Sun and alter its interior structure. It formulates the capture dynamics with a two-component rate equation $\\frac{dN_\\chi}{dt} = C_{\\chi N} + C_{\\chi\\chi} N_\\chi$, showing that self-capture can yield exponential growth and lead to a nearly fixed solar abundance $N_\\chi/N_\\odot \\sim 2\\times 10^{-11}$ for $m_\\chi \\approx 5$ GeV. This ADM-induced opacity modification, equivalent to a local opacity change of about 10%, lowers the convective-zone radius by ~0.7% and shifts the solar neutrino fluxes downward (e.g., $\\delta\\Phi_\\mathrm{B} \\sim -17\\%$, $\\delta\\Phi_\\mathrm{Be} \\sim -6.7\\%$). The results address the solar composition problem and connect dark matter microphysics to helioseismology and low-energy solar neutrino measurements, offering testable predictions for Borexino and SNO+ and compatibility with light ADM hints from direct detection.

Abstract

Cold dark matter particles with an intrinsic matter-antimatter asymmetry do not annihilate after gravitational capture by the Sun and can affect its interior structure. The rate of capture is exponentially enhanced when such particles have self-interactions of the right order to explain structure formation on galactic scales. A `dark baryon' of mass 5 GeV is a natural candidate and has the required relic abundance if its asymmetry is similar to that of ordinary baryons. We show that such particles can solve the `solar composition problem'. The predicted small decrease in the low energy neutrino fluxes may be measurable by the Borexino and SNO+ experiments.

Asymmetric dark matter and the Sun

TL;DR

The paper investigates whether asymmetric dark matter (ADM) with self-interactions can accumulate in the Sun and alter its interior structure. It formulates the capture dynamics with a two-component rate equation , showing that self-capture can yield exponential growth and lead to a nearly fixed solar abundance for GeV. This ADM-induced opacity modification, equivalent to a local opacity change of about 10%, lowers the convective-zone radius by ~0.7% and shifts the solar neutrino fluxes downward (e.g., , ). The results address the solar composition problem and connect dark matter microphysics to helioseismology and low-energy solar neutrino measurements, offering testable predictions for Borexino and SNO+ and compatibility with light ADM hints from direct detection.

Abstract

Cold dark matter particles with an intrinsic matter-antimatter asymmetry do not annihilate after gravitational capture by the Sun and can affect its interior structure. The rate of capture is exponentially enhanced when such particles have self-interactions of the right order to explain structure formation on galactic scales. A `dark baryon' of mass 5 GeV is a natural candidate and has the required relic abundance if its asymmetry is similar to that of ordinary baryons. We show that such particles can solve the `solar composition problem'. The predicted small decrease in the low energy neutrino fluxes may be measurable by the Borexino and SNO+ experiments.

Paper Structure

This paper contains 3 sections, 6 equations, 3 figures.

Table of Contents

  1. Capture of self-interacting ADM
  2. Helioseismology and Solar neutrinos
  3. Conclusions

Figures (3)

  • Figure 1: Growth of the relative abundance of 5 GeV mass ADM particles in the Sun until its present age (vertical line) assuming $s_{\chi\chi} = 2 \times 10^{-24} \mathrm{cm}^2 \mathrm{GeV}^{-1}$, and $\sigma_{\chi N} = 10^{-39}~\mathrm{cm}^2$ (solid line) and $10^{-36}~\mathrm{cm}^2$ (dashed line), these being the maximum experimentally allowed values for spin-independent and spin-dependent interactions respectively. Also shown is the 'black disk' limit (dotted line) for the Sun.
  • Figure 2: The radial variation of $\delta L(r) \equiv L_\chi(r)/L_{\odot}(r)$ due to ADM of mass 5 GeV, using the approximation of Ref.Spergel:1984re and $L_\odot (r)$ from the BS05 (OP) Standard Solar Model Bahcall:2004pz.
  • Figure 3: Neutrino producing regions in the solar interior