Einasto potential¶

class galpy.potential.EinastoPotential(amp=1.0, h=2.0, n=1, rs=None, rm2=None, normalize=False, ro=None, vo=None)[source]¶

Potential with an Einasto [1] density. Class implements the following interchangeable conventions:

\[\rho(r) = \mathrm{amp}\,\exp\left(-d_n\left[\left(\frac{r}{r_s}\right)^\frac{1}{n}-1\right]\right)\]

or

\[\rho(r) = \mathrm{amp}\,\exp\left(-2n\left[\left(\frac{r}{r_{-2}}\right)^\frac{1}{n}-1\right]\right)\]

or

\[\rho(r) = \mathrm{amp}\,\exp\left(-\left(\frac{r}{h}\right)^\frac{1}{n}\right)\]

With conventions taken from [2].

__init__(amp=1.0, h=2.0, n=1, rs=None, rm2=None, normalize=False, ro=None, vo=None)[source]¶

Initialize a Einasto-density potential [1].

Parameters:

amp (float or Quantity) – Amplitude to be applied to the potential. Can be a Quantity with units of mass density or Gxmass density.
h (float or Quantity) – Scale length.
rs (float or Quantity) – Radius of the sphere that contains half of the total mass.
rm2 (float or Quantity) – Radius at which rho(r) ∝ r^-2.
n (float) – The Einasto index. A shape parameter defining the steepness of the power law
normalize (bool or float, optional) – 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. Default is False.
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

References