Galaxy-formation bound on the cosmological constant
= Galaxy-formation bound on the cosmological constant
If a perturbation has amplitude $A\ll1$ at decoupling, it needs a growth factor of at least $A^{-1}$ before cosmological-constant domination freezes its growth. The order-of-magnitude requirement is
$$
\rho_\Lambda\lesssim A^3\rho_m(t_{\rm dec}),
$$
up to the collapse threshold and the gradual transition encoded by the exact growth factor.