Flattened Power-law potential¶
Flattening is in the potential as in Evans (1994) rather than in the density
- class galpy.potential.FlattenedPowerPotential(amp=1.0, alpha=0.5, q=0.9, core=1e-08, normalize=False, r1=1.0, ro=None, vo=None)[source]¶
Class that implements a power-law potential that is flattened in the potential (NOT the density)
\[\Phi(R,z) = -\frac{\mathrm{amp}\,r_1^\alpha}{\alpha\,\left(R^2+(z/q)^2+\mathrm{core}^2\right)^{\alpha/2}}\]and the same as LogarithmicHaloPotential for \(\alpha=0\)
See Figure 1 in Evans (1994) for combinations of alpha and q that correspond to positive densities
- __init__(amp=1.0, alpha=0.5, q=0.9, core=1e-08, normalize=False, r1=1.0, ro=None, vo=None)[source]¶
NAME:
__init__
PURPOSE:
initialize a flattened power-law potential
INPUT:
amp - amplitude to be applied to the potential (default: 1); can be a Quantity with units of velocity-squared
alpha - power
q - flattening
core - core radius (can be Quantity)
r1= (1.) reference radius for amplitude (can be Quantity)
normalize - if True, normalize such that vc(1.,0.)=1., or, if given as a number, such that the force is this fraction of the force necessary to make vc(1.,0.)=1.
ro=, vo= distance and velocity scales for translation into internal units (default from configuration file)
OUTPUT:
(none)
HISTORY:
2013-01-09 - Written - Bovy (IAS)