Logarithmic halo potential¶
- class galpy.potential.LogarithmicHaloPotential(amp=1.0, core=1e-08, q=1.0, b=None, normalize=False, ro=None, vo=None)[source]¶
Class that implements the logarithmic potential
\[\Phi(R,z) = \frac{\mathrm{amp}}{2}\,\ln\left[R^2+\left(\frac{z}{q}\right)^2+\mathrm{core}^2\right]\]Alternatively, the potential can be made triaxial by adding a parameter \(b\)
\[\Phi(x,y,z) = \frac{\mathrm{amp}}{2}\,\ln\left[x^2+\left(\frac{y}{b}\right)^2+\left(\frac{z}{q}\right)^2+\mathrm{core}^2\right]\]With these definitions, \(\sqrt{\mathrm{amp}}\) is the circular velocity at \(r \gg \mathrm{core}\) at \((y,z) = (0,0)\).
- __init__(amp=1.0, core=1e-08, q=1.0, b=None, normalize=False, ro=None, vo=None)[source]¶
NAME:
__init__
PURPOSE:
initialize a logarithmic potential
INPUT:
amp - amplitude to be applied to the potential (default: 1); can be a Quantity with units of velocity-squared
core - core radius at which the logarithm is cut (can be Quantity)
q - potential flattening (z/q)**2.
b= (None) if set, shape parameter in y-direction (y –> y/b; see definition)
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:
2010-04-02 - Started - Bovy (NYU)