Class that implements a steady-state spiral potential
V(r,phi,t) = A(t)/alpha cos(alpha ln(r) - m(phi - Omegas*t-gamma))
where
A(t) = A_max exp(- [t-to]^2/sigma^2/2.)
NAME:
__init__
PURPOSE:
initialize a transient logarithmic spiral potential localized around to
INPUT:
amp - amplitude to be applied to the potential (default: 1., A below)
gamma - angle between sun-GC line and the line connecting the peak of the spiral pattern at the Solar radius (in rad; default=45 degree)
A - force amplitude (alpha*potential-amplitude; default=0.035)
omegas= - pattern speed (default=0.65)
m= number of arms
to= time at which the spiral peaks
sigma= “spiral duration” (sigma in Gaussian amplitude)
Either provide:
- alpha=
- p= pitch angle (rad)
OUTPUT:
(none)
HISTORY:
2011-03-27 - Started - Bovy (NYU)