pynbody.analysis.angmom.spin_parameter#
- pynbody.analysis.angmom.spin_parameter(snap)[source]#
Return the spin parameter lambda’ of a centered halo
The spin parameter is defined as in eq. (5) of Bullock et al. 2001 (2001MNRAS.321..559B).
Note that the halo has to be aligned such that its center is the coordinate origin and the velocity must be zeroed. If you are not sure whether this will be true, calculate the spin parameter of h using:
>>> with pynbody.analysis.angmom.faceon(h): >>> spin = pynbody.analysis.angmom.spin_parameter(h)
- Parameters:
snap (SimSnap) – The snapshot to analyze
- Returns:
The dimensionless spin parameter lambda’ of the halo
- Return type:
float