Dehnen-like smoothing wrapper potential

class galpy.potential.DehnenSmoothWrapperPotential(*args, **kwargs)

Potential wrapper class that implements the growth of a gravitational potential following Dehnen (2000). The amplitude A applied to a potential wrapped by an instance of this class is changed as

\[A(t) = amp\,\left(\frac{3}{16}\xi^5-\frac{5}{8}\xi^3+\frac{15}{16}\xi+\frac{1}{2}\right)\]

where

\[\begin{split}\xi = \begin{cases} -1 & t < t_\mathrm{form}\\ 2\left(\frac{t-t_\mathrm{form}}{t_\mathrm{steady}}\right)-1\,, & t_\mathrm{form} \leq t \leq t_\mathrm{form}+t_\mathrm{steady}\\ 1 & t > t_\mathrm{form}+t_\mathrm{steady} \end{cases}\end{split}\]

if decay=True, the amplitude decays rather than grows as decay = 1 - grow.

__init__(amp=1.0, pot=None, tform=-4.0, tsteady=None, decay=False, ro=None, vo=None)

Initialize a DehnenSmoothWrapper Potential.

Parameters:

• amp (float, optional) – Amplitude to be applied to the potential (default: 1.).

• pot (Potential instance or list thereof, optional) – The amplitude of this will be grown by this wrapper.

• tform (float or Quantity, optional) – Start of growth (default: -4.0).

• tsteady (float or Quantity, optional) – Time from tform at which the potential is fully grown (default: -tform/2, so the perturbation is fully grown at tform/2).

• decay (bool, optional) – If True, decay the amplitude instead of growing it (as 1-grow).

• ro (float or Quantity, optional) – Distance scale for translation into internal units (default from configuration file).

• vo (float or Quantity, optional) – Velocity scale for translation into internal units (default from configuration file).

Notes

• 2017-06-26 - Started - Bovy (UofT)

• 2018-10-07 - Added ‘decay’ option - Bovy (UofT)