Lopsided disk potential

Like in Kuijken & Tremaine, but for m=1

class galpy.potential.LopsidedDiskPotential(amp=1.0, phib=0.4363323129985824, p=1.0, phio=0.01, tform=None, tsteady=None, cp=None, sp=None)

Class that implements the disk potential

\[\Phi(R,\phi) = \phi_0\,R^p\,\cos\left(\phi-\phi_b\right)\]

See documentation for CosmphiDiskPotential

__init__(amp=1.0, phib=0.4363323129985824, p=1.0, phio=0.01, tform=None, tsteady=None, cp=None, sp=None)

NAME:

__init__

PURPOSE:

initialize an cosmphi disk potential

phi(R,phi) = phio (R/Ro)^p cos[m(phi-phib)]

INPUT:

amp= amplitude to be applied to the potential (default: 1.), see twophio below

tform= start of growth (to smoothly grow this potential

tsteady= time delay at which the perturbation is fully grown (default: 2.)

m= cos( m * (phi - phib) )

p= power-law index of the phi(R) = (R/Ro)^p part

Either:

  1. phib= angle (in rad; default=25 degree)

    phio= potential perturbation (in terms of phio/vo^2 if vo=1 at Ro=1)

  2. cp, sp= m * phio * cos(m * phib), m * phio * sin(m * phib)

OUTPUT:

(none)

HISTORY:

2011-10-27 - Started - Bovy (IAS)