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Linear density-perturbation growth

What you are seeing: the linear growth of matter density perturbations in a flat Λ\LambdaCDM universe. δ∝a\delta \propto a during matter domination; Lambda freezes the growth at late times. The growth factor f(a)=dln⁡δ/dln⁡a≈Ωm(a)0.55f(a) = d\ln\delta/d\ln a \approx \Omega_m(a)^{0.55} tracks the transition.

Figure 1. Growth factor and δ(a)\delta(a) for Ωm=0.315\Omega_m = 0.315.
Ω_m,00.315

WHAT TO TRY

  • Vary each control and watch the rail readouts respond.
  • Compare the diagnostic plot against the live scene.