Potential (galpy.potential
)¶
3D potentials¶
General instance routines¶
Use as Potential-instance.method(...)
In addition to these, the NFWPotential
also has methods to calculate virial quantities
General 3D potential routines¶
Use as method(...)
- dvcircdR
- epifreq
- evaluateDensities
- evaluatephiforces
- evaluatePotentials
- evaluateR2derivs
- evaluateRzderivs
- evaluateRforces
- evaluaterforces
- evaluatez2derivs
- evaluatezforces
- flattening
- lindbladR
- nemo_accname
- nemo_accpars
- omegac
- plotDensities
- plotEscapecurve
- plotPotentials
- plotRotcurve
- rl
- turn_physical_off
- turn_physical_on
- vcirc
- verticalfreq
- vesc
- vterm
In addition to these, the following methods are available to compute expansion coefficients for the SCFPotential
class for a given density
Specific potentials¶
Spherical potentials¶
Axisymmetric potentials¶
- Double exponential disk potential
- Flattened Power-law potential
- Interpolated axisymmetric potential
- Interpolated SnapshotRZ potential
- Kuzmin disk potential
- Kuzmin-Kutuzov Staeckel potential
- Logarithmic halo potential
- Miyamoto-Nagai potential
- Three Miyamoto-Nagai disk approximation to an exponential disk
- Razor-thin exponential disk potential
- Axisymmetrized N-body snapshot potential
Triaxial potentials¶
In addition to these classes, a simple Milky-Way-like potential fit to
data on the Milky Way is included as
galpy.potential.MWPotential2014
(see the galpy
paper for
details). Note that this potential assumes a circular velocity of 220
km/s at the solar radius at 8 kpc; see arXiv/1412.3451 for full information on how this
potential was fit. This potential is defined as
>>> bp= PowerSphericalPotentialwCutoff(alpha=1.8,rc=1.9/8.,normalize=0.05)
>>> mp= MiyamotoNagaiPotential(a=3./8.,b=0.28/8.,normalize=.6)
>>> np= NFWPotential(a=16/8.,normalize=.35)
>>> MWPotential2014= [bp,mp,np]
and can thus be used like any list of Potentials
. If one wants to
add the supermassive black hole at the Galactic center, this can be
done by
>>> from galpy.potential import KeplerPotential
>>> from galpy.util import bovy_conversion
>>> MWPotential2014.append(KeplerPotential(amp=4*10**6./bovy_conversion.mass_in_msol(220.,8.)))
for a black hole with a mass of \(4\times10^6\,M_{\odot}\).
As explained in this section, without this black
hole MWPotential2014
can be used with Dehnen’s gyrfalcON code
using accname=PowSphwCut+MiyamotoNagai+NFW
and
accpars=0,1001.79126907,1.8,1.9#0,306770.418682,3.0,0.28#0,16.0,162.958241887
.
An older version galpy.potential.MWPotential
of a similar
potential that was not fit to data on the Milky Way is defined as
>>> mp= MiyamotoNagaiPotential(a=0.5,b=0.0375,normalize=.6)
>>> np= NFWPotential(a=4.5,normalize=.35)
>>> hp= HernquistPotential(a=0.6/8,normalize=0.05)
>>> MWPotential= [mp,np,hp]
galpy.potential.MWPotential2014
supersedes
galpy.potential.MWPotential
.
2D potentials¶
General instance routines¶
Use as Potential-instance.method(...)
General axisymmetric potential instance routines¶
Use as Potential-instance.method(...)
General 2D potential routines¶
Use as method(...)
Specific potentials¶
All of the 3D potentials above can be used as two-dimensional potentials in the mid-plane.
In addition, a two-dimensional bar potential and a two spiral potentials are included