Transient logarithmic spiral potential¶
- class galpy.potential.TransientLogSpiralPotential(amp=1.0, omegas=0.65, A=-0.035, alpha=-7.0, m=2, gamma=0.7853981633974483, p=None, sigma=1.0, to=0.0, ro=None, vo=None)[source]¶
Class that implements a steady-state spiral potential
\[\Phi(R,\phi) = \frac{\mathrm{amp}(t)}{\alpha}\,\cos\left(\alpha\,\ln R - m\,(\phi-\Omega_s\,t-\gamma)\right)\]where
\[\mathrm{amp}(t) = \mathrm{amp}\,\times A\,\exp\left(-\frac{[t-t_0]^2}{2\,\sigma^2}\right)\]- __init__(amp=1.0, omegas=0.65, A=-0.035, alpha=-7.0, m=2, gamma=0.7853981633974483, p=None, sigma=1.0, to=0.0, ro=None, vo=None)[source]¶
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; can be Quantity)
A - amplitude (alpha*potential-amplitude; default=0.035; can be Quantity)
omegas= - pattern speed (default=0.65; can be Quantity)
m= number of arms
to= time at which the spiral peaks (can be Quantity)
sigma= “spiral duration” (sigma in Gaussian amplitude; can be Quantity)
Either provide:
alpha=
p= pitch angle (rad; can be Quantity)
OUTPUT:
(none)
HISTORY:
2011-03-27 - Started - Bovy (NYU)