Three Miyamoto-Nagai disk approximation to an exponential disk

class galpy.potential.MN3ExponentialDiskPotential(amp=1.0, hr=0.3333333333333333, hz=0.0625, sech=False, posdens=False, normalize=False, ro=None, vo=None)[source]

class that implements the three Miyamoto-Nagai approximation to a radially-exponential disk potential of Smith et al. 2015

\[\rho(R,z) = \mathrm{amp}\,\exp\left(-R/h_R-|z|/h_z\right)\]

or

\[\rho(R,z) = \mathrm{amp}\,\exp\left(-R/h_R\right)\mathrm{sech}^2\left(-|z|/h_z\right)\]

depending on whether sech=True or not. This density is approximated using three Miyamoto-Nagai disks

__init__(amp=1.0, hr=0.3333333333333333, hz=0.0625, sech=False, posdens=False, normalize=False, ro=None, vo=None)[source]

Initialize a 3MN approximation to an exponential disk potential.

Parameters:
  • amp (float or Quantity, optional) – Amplitude to be applied to the potential (default: 1); can be a Quantity with units of mass density or Gxmass density.

  • hr (float or Quantity, optional) – Disk scale-length.

  • hz (float or Quantity, optional) – Scale-height.

  • sech (bool, optional) – If True, hz is the scale height of a sech vertical profile (default is exponential vertical profile).

  • posdens (bool, optional) – If True, allow only positive density solutions (Table 2 in Smith et al. rather than Table 1).

  • 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.

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

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

Notes

  • 2015-02-07 - Written - Bovy (IAS)