Corotating rotation wrapper potential¶
- class galpy.potential.CorotatingRotationWrapperPotential(*args, **kwargs)[source]¶
Potential wrapper class that implements rotation with fixed R x pattern-speed around the z-axis. Can be used to make spiral structure that is everywhere co-rotating. The potential is rotated by replacing
\[\phi \rightarrow \phi + \frac{V_p(R)}{R} \times \left(t-t_0\right) + \mathrm{pa}\]with \(V_p(R)\) the circular velocity curve, \(t_0\) a reference time—time at which the potential is unchanged by the wrapper—and \(\mathrm{pa}\) the position angle at \(t=0\). The circular velocity is parameterized as
\[V_p(R) = V_{p,0}\,\left(\frac{R}{R_0}\right)^\beta\,.\]- __init__(amp=1.0, pot=None, vpo=1.0, beta=0.0, to=0.0, pa=0.0, ro=None, vo=None)[source]¶
NAME:
__init__
PURPOSE:
initialize a CorotatingRotationWrapper Potential
INPUT:
amp - amplitude to be applied to the potential (default: 1.)
pot - Potential instance or list thereof; this potential is made to rotate around the z axis by the wrapper
vpo= (1.) amplitude of the circular-velocity curve (can be a Quantity)
beta= (0.) power-law amplitude of the circular-velocity curve
to= (0.) reference time at which the potential == pot
pa= (0.) the position angle (can be a Quantity)
OUTPUT:
(none)
HISTORY:
2018-02-21 - Started - Bovy (UofT)