UniformWedgeFlow

class dysmalpy.models.UniformWedgeFlow(**kwargs)

Bases: HigherOrderKinematicsPerturbation, _DysmalFittable3DModel

Model for a uniform planar radial flow (only in the plane of the galaxy),

but that only has flow within two wedges of a given opening angle, centered at an angle phi relative to the galaxy major axis.

Parameters:

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

• theta (float) – Opening angle of wedge (the full angular span)

• phi (float) – Angle offset relative to the galaxy angle, so the wedge center is at phi. (phi_gal - phi)

Attributes Summary

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

Methods Summary

evaluate(x, y, z, vr, theta, phi)	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', 'theta', 'phi')

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.

phi = DysmalParameter('phi', value=0.0, bounds=(0.0, 360.0), prior=<dysmalpy.parameters.UniformPrior object>)

theta = DysmalParameter('theta', value=60.0, bounds=(0.0, 180.0), prior=<dysmalpy.parameters.UniformPrior object>)

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

Methods Documentation

evaluate(x, y, z, vr, theta, phi)

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