= Scale-free characteristic mass in the Press-Schechter formalism
{title2=$M_*\propto D^{1/s},\quad \sigma(M)\propto M^{-s}$}
If the linearly extrapolated rms amplitude scales as $\sigma(M)\propto M^{-s}$, a fixed peak-height cutoff in the <Press-Schechter halo mass function> has $M_*\propto D^{1/s}$, where $D$ is the <linear growth factor>. The differential prefactor scales as $M^{s-2}$ and the exponential argument as $M^{2s}$. The cutoff convention must be stated when fixing its absolute normalization: $\nu=1$ and $\nu^2/2=1$ select different masses, although their redshift scaling is the same.
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