galpy.potential.LinShuReductionFactor

galpy.potential.LinShuReductionFactor(axiPot, R, sigmar, nonaxiPot=None, k=None, m=None, OmegaP=None)

NAME:

LinShuReductionFactor

PURPOSE:

Calculate the Lin & Shu (1966) reduction factor: the reduced linear response of a kinematically-warm stellar disk to a perturbation

INPUT:

axiPot - The background, axisymmetric potential

R - Cylindrical radius

sigmar - radial velocity dispersion of the population

Then either provide:

  1. m= m in the perturbation’s m x phi (number of arms for a spiral)

    k= wavenumber (see Binney & Tremaine 2008)

    OmegaP= pattern speed

  2. nonaxiPot= a non-axisymmetric Potential instance (such as SteadyLogSpiralPotential) that has functions that return OmegaP, m, and wavenumber

OUTPUT:

reduction factor

HISTORY:

2014-08-23 - Written - Bovy (IAS)