PlanarUniformRadialFlow

class dysmalpy.models.PlanarUniformRadialFlow(**kwargs)

Bases: HigherOrderKinematicsPerturbation, _DysmalFittable3DModel

Model for a planar uniform radial flow, with radial flow only in the plane of the galaxy.

Parameters:

vr (float) – Radial velocity in km/s. vr > 0 for outflow, vr < 0 for inflow

Notes

This model simply adds a constant radial velocity component to all of the positions in the galaxy.

Attributes Summary

outputs
param_names	Names of the parameters that describe models of this type.
vr

Methods Summary

evaluate(x, y, z, vr)	Evaluate the radial velocity as a function of position x, y, z
vel_direction_emitframe(x, y, z[, _save_memory])	Method to return the velocity direction in the galaxy Cartesian frame.
velocity(x, y, z, *args)	Return the velocity as a function of x, y, z

Attributes Documentation

outputs = ('vrad',)

param_names = ('vr',)

Names of the parameters that describe models of this type.

The parameters in this tuple are in the same order they should be passed in when initializing a model of a specific type. Some types of models, such as polynomial models, have a different number of parameters depending on some other property of the model, such as the degree.

When defining a custom model class the value of this attribute is automatically set by the Parameter attributes defined in the class body.

vr = DysmalParameter('vr', value=30.0, prior=<dysmalpy.parameters.UniformPrior object>)

Methods Documentation

static evaluate(x, y, z, vr)

Evaluate the radial velocity as a function of position x, y, z

vel_direction_emitframe(x, y, z, _save_memory=False)

Method to return the velocity direction in the galaxy Cartesian frame.

Parameters:

• x (float or array) – xyz position in the radial flow reference frame.

• y (float or array) – xyz position in the radial flow reference frame.

• z (float or array) – xyz position in the radial flow reference frame.

• _save_memory (bool, optional) – Option to save memory by only calculating the relevant matrices (eg during fitting). Default: False

Returns:

vel_dir_unit_vector – Direction of the velocity vector in (xyz).

For a planar uniform radial flow, this is the +Rhat direction, in cylindrical coordinates (R,phi,z).

Return type:

3-element array

velocity(x, y, z, *args)

Return the velocity as a function of x, y, z