# Softened-needle bar potential¶

class galpy.potential.SoftenedNeedleBarPotential(amp=1.0, a=4.0, b=0.0, c=1.0, normalize=False, pa=0.4, omegab=1.8, ro=None, vo=None)

Class that implements the softened needle bar potential from Long & Murali (1992)

$\Phi(x,y,z) = \frac{\mathrm{amp}}{2a}\,\ln\left(\frac{x-a+T_-}{x+a+T_+}\right)$

where

$T_{\pm} = \sqrt{(a\pm x)^2 + y^2+(b+\sqrt{z^2+c^2})^2}$

For a prolate bar, set $$b$$ to zero.

__init__(amp=1.0, a=4.0, b=0.0, c=1.0, normalize=False, pa=0.4, omegab=1.8, ro=None, vo=None)

NAME:

__init__

PURPOSE:

initialize a softened-needle bar potential

INPUT:

amp - amplitude to be applied to the potential (default: 1); can be a Quantity with units of mass

a= (4.) Bar half-length (can be Quantity)

b= (1.) Triaxial softening length (can be Quantity)

c= (1.) Prolate softening length (can be Quantity)

pa= (0.4) The position angle of the x axis (rad or Quantity)

omegab= (1.8) Pattern speed (can be Quantity)

normalize - if True, normalize such that vc(1.,0.)=1., or, if given as a number, such that the force is this fraction of the force necessary to make vc(1.,0.)=1.

ro=, vo= distance and velocity scales for translation into internal units (default from configuration file)

OUTPUT:

(none)

HISTORY:

2016-11-02 - Started - Bovy (UofT)