# NFW potential¶

class galpy.potential.NFWPotential(amp=1.0, a=1.0, normalize=False, rmax=None, vmax=None, conc=None, mvir=None, vo=None, ro=None, H=70.0, Om=0.3, overdens=200.0, wrtcrit=False)[source]

Class that implements the NFW potential

$\rho(r) = \frac{\mathrm{amp}}{4\,\pi\,a^3}\,\frac{1}{(r/a)\,(1+r/a)^{2}}$
__init__(amp=1.0, a=1.0, normalize=False, rmax=None, vmax=None, conc=None, mvir=None, vo=None, ro=None, H=70.0, Om=0.3, overdens=200.0, wrtcrit=False)[source]

Initialize a NFW Potential.

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

• a (float or Quantity, optional) – Scale radius (can be Quantity).

• 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.

• rmax (float or Quantity, optional) – Radius where the rotation curve peak.

• vmax (float or Quantity, optional) – Maximum circular velocity.

• conc (float, optional) – Concentration.

• mvir (float, optional) – virial mass in 10^12 Msolar

• H (float, optional) – Hubble constant in km/s/Mpc.

• Om (float, optional) – Omega matter.

• overdens (float, optional) – Overdensity which defines the virial radius.

• wrtcrit (bool, optional) – If True, the overdensity is wrt the critical density rather than the mean matter density.

• 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

• Initialize with one of:
• a and amp or normalize

• rmax and vmax

• conc, mvir, H, Om, overdens, wrtcrit

• 2010-07-09 - Written - Bovy (NYU)

• 2014-04-03 - Initialization w/ concentration and mass - Bovy (IAS)

• 2020-04-29 - Initialization w/ rmax and vmax - Bovy (UofT)