# Corotating rotation wrapper potential¶

class galpy.potential.CorotatingRotationWrapperPotential(amp=1.0, pot=None, vpo=1.0, beta=0.0, to=0.0, pa=0.0, ro=None, vo=None)[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)