# 10.1. Overdensity $$\Delta(z)$$ descriptions¶

Possible keyword choices for the gCOSMO_FLAG_DELTA_REF parameter.

 Keyword Description kRHO_CRIT $$\Delta(z) = \Delta_{\rm crit}$$ kRHO_MEAN $$\Delta(z) = \Delta_{\rm crit} \times \Omega_{\rm m}(z)$$ kBRYANNORMAN98 Using the formula by Bryan and Norman (1998) for a flat Universe

Note

$$\Delta_{\rm crit}$$ is the constant overdensity factor set via the gCOSMO_DELTA0 input parameter. See also Section 6.7, Cosmology (cosmo.h).