Class that implements the NFW potential
NAME:
__init__
PURPOSE:
Initialize a NFW potential
INPUT:
amp - amplitude to be applied to the potential
a - “scale” (in terms of Ro)
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.
Alternatively, NFW potentials can be initialized using
conc= concentration
mvir= virial mass in 10^12 Msolar
in which case you also need to supply the following keywords
vo= (220.) velocity unit in km/s
ro= (8.) length unit in kpc
H= (default: 70) Hubble constant in km/s/Mpc
Om= (default: 0.3) Omega matter
overdens= (200) overdensity which defines the virial radius
wrtcrit= (False) if True, the overdensity is wrt the critical density rather than the mean matter density
OUTPUT:
(none)
HISTORY:
2010-07-09 - Written - Bovy (NYU)
2014-04-03 - Initialization w/ concentration and mass - Bovy (IAS)