halotools.empirical_models.halo_mass_to_virial_velocity(total_mass, cosmology, redshift, mdef)[source] [edit on github]

The circular velocity evaluated at the halo boundary, \(V_{\rm vir} \equiv \sqrt{GM_{\rm halo}/R_{\rm halo}}\).


total_mass : array_like

Total mass of the halo; can be a scalar or numpy array.

cosmology : object

Instance of an Astropy cosmology object.

redshift: array_like

Can either be a scalar, or a numpy array of the same dimension as the input mass.

mdef: str

String specifying the halo mass definition, e.g., ‘vir’ or ‘200m’.


vvir : array_like

Virial velocity in km/s.


See Spatial Profiles of Halos for derivations and implementation details.