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WIMP Thermal Freeze-Out: Dark Matter Relic Abundance

Solve the Boltzmann freeze-out equation live: watch a WIMP's comoving abundance decouple from thermal equilibrium as the universe expands, and see how mass and annihilation cross-section set today's dark matter density (the 'WIMP miracle').

Space & Astronomy3DAdvanced60 FPS📱 Mobile-adapted⇄ 2D version

Every popular dark-matter candidate — a WIMP, an axion, a sterile neutrino — has to explain the same number: today's measured dark-matter density, Ω_DMh² ≈ 0.12. For a thermal WIMP that number falls straight out of one calculation: solving the Boltzmann equation for a particle's comoving abundance as it freezes out of chemical equilibrium in the expanding early universe. This simulator integrates that equation numerically (RK4, in dimensionless x = m_χ/T) for the mass and annihilation cross-section you choose, plays back the resulting decoupling as a shrinking cube of comoving particles, and plots the abundance against its instantaneous equilibrium value on a live log-log curve — reproducing the celebrated "WIMP miracle" coincidence between weak-scale physics and the observed relic density.

⚙ Under the hood

Numerically integrate the Boltzmann freeze-out equation for a WIMP dark-matter candidate and watch its comoving abundance decouple from thermal equilibrium as the universe expands, reproducing the 'WIMP miracle' link between weak-scale physics and the observed relic density.

dark mattercosmologyparticle physicsBoltzmann equationWIMPrelic density

3D · Three.js / WebGL renderer · 60 FPS target · runs fully client-side, no install