Geometry

class dysmalpy.models.Geometry(obs_name=None, **kwargs)[source]

Bases: _DysmalFittable3DModel

Model component defining the transformation from galaxy to sky coordinates

Parameters:

inc (float) – Inclination of the model in degrees
pa (float) – Position angle East of North of the blueshifted side of the model in degrees
xshift (float) – x-coordinate of the center of the model relative to center of data cube in pixels
yshift (float) – y-coordinate of the center of the model relative to center of data cube in pixels
vel_shift (float) – Systemic velocity shift that will be applied to the whole cube in km/s
obs_name (string) – (Attribute): Name of the observation to which this geometry belongs.

coord_transform:: Transform from sky to galaxy coordinates.

inverse_coord_transform:: Transform from galaxy to sky coordinates.

Notes

This model component takes as input sky coordinates and converts them to galaxy frame coordinates. vel_shift instead is used within ModelSet.simulate_cube to apply the necessary velocity shift.

Attributes Summary

`inc`
`obs_name`
`outputs`
`pa`
`param_names`	Names of the parameters that describe models of this type.
`vel_shift`
`xshift`
`yshift`

Methods Summary

`LOS_direction_emitframe`([inc])	Method to return the LOS direction in terms of the emission frame.
`coord_transform`(x, y, z[, inc, pa, xshift, ...])	Transform sky coordinates to galaxy/model reference frame
`evaluate`(x, y, z, inc, pa, xshift, yshift, ...)	Transform sky coordinates to galaxy/model reference frame
`inverse_coord_transform`(xgal, ygal, zgal[, ...])	Transform galaxy/model reference frame to sky coordinates
`project_velocity_along_LOS`(model, vel, x, y, z)	Method to project velocities in models' emission frame along the LOS (zsky direction).
`transform_cube_affine`(cube[, inc, pa, ...])	Incline and transform a cube from galaxy/model reference frame to sky frame.

Attributes Documentation

inc = DysmalParameter('inc', value=45.0, bounds=(0, 90), prior=<dysmalpy.parameters.UniformPrior object>)

obs_name = 'galaxy'

outputs = ('xp', 'yp', 'zp')

pa = DysmalParameter('pa', value=0.0, bounds=(-180, 180), prior=<dysmalpy.parameters.UniformPrior object>)

param_names = ('inc', 'pa', 'xshift', 'yshift', 'vel_shift')

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.

vel_shift = DysmalParameter('vel_shift', value=0.0, fixed=True, prior=<dysmalpy.parameters.UniformPrior object>)

xshift = DysmalParameter('xshift', value=0.0, prior=<dysmalpy.parameters.UniformPrior object>)

yshift = DysmalParameter('yshift', value=0.0, prior=<dysmalpy.parameters.UniformPrior object>)

Methods Documentation

LOS_direction_emitframe(inc=None)[source]

Method to return the LOS direction in terms of the emission frame. This just accounts for the inclination.

Returns:

LOS_unit_vector – Direction of the LOS vector in (xyz).

This describes the inclination, so returns [0, sin(i), -cos(i)] Note the zsky direction is TOWARDS from the observer, so the LOS is -zsky, where zsky is in the direction [0, -sin(i), cos(i)].

Return type:

3-element array

coord_transform(x, y, z, inc=None, pa=None, xshift=None, yshift=None)[source]: Transform sky coordinates to galaxy/model reference frame

static evaluate(x, y, z, inc, pa, xshift, yshift, vel_shift)[source]: Transform sky coordinates to galaxy/model reference frame

inverse_coord_transform(xgal, ygal, zgal, inc=None, pa=None, xshift=None, yshift=None)[source]: Transform galaxy/model reference frame to sky coordinates

project_velocity_along_LOS(model, vel, x, y, z, inc=None)[source]

Method to project velocities in models’ emission frame along the LOS (zsky direction).

Parameters:

model (_DysmalModel) – Model component from which the velocity was calculated.
vel (float or array or tuple of arrays) – Amplitude of the velocity. If model._multicoord_velocity is True, must pass a tuple of velocity components for each coordinate in the model’s native geometry.
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.
inc (float, optional) – Specify a separate inclination. Default: uses self.inc

Returns:

v_LOS – Projection of velocity ‘vel’ along the LOS.

Return type:

float or array

transform_cube_affine(cube, inc=None, pa=None, xshift=None, yshift=None, output_shape=None)[source]: Incline and transform a cube from galaxy/model reference frame to sky frame. Use scipy.ndimage.affine_transform