= Halo baryon-to-star conversion efficiency
{title2=$\epsilon_*=M_*/(f_bM_h)$}
= Halo star-formation efficiency
{synonym}
The integrated <halo star-formation efficiency> is the fraction of a <dark-matter halo>'s reference baryonic mass converted into stars: $\epsilon_*=M_*/(f_bM_h)$, with <cosmic baryon fraction> $f_b$. It is distinct from <star-formation efficiency per free-fall time>. Cooling, gas supply and retention, <stellar feedback> and <active-galactic-nucleus feedback> make it strongly dependent on <dark-matter halo> mass. With stellar <mass-to-light ratio> $\Upsilon_*$, a simple central-galaxy mapping is $L=\epsilon_*f_bM_h/\Upsilon_*$. Changing this efficiency changes both the mapping and the logarithmic Jacobian between the <dark-matter halo> mass function and the <luminosity function>.
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