widget_SPARC

A module for handling the SPARC widget, notebook 09_Widget_SPARC_Galaxies.ipynb.

ToC: Functions

bulge(r, bpref)	Interpolating the bulge velocity.
disk(r, dpref)	Interpolating the disk velocity.
gas(r)	Interpolating the gas velocity.
halo(r, rc, rho0)	Function to calculate the gravitational effect of a Dark Matter halo using the isothermal density profile (Source: [Jimenez2003]).
totalcurve(r, bpref, dpref, rc, rho0)	Function to calculate the total gravitational effect of all components of a galaxy.
widgetfunction(bpref, dpref, rc, rho0)	Generate a plot for use with interactive rotation curve plot of SPARC data with sliders for parameters.
interactive_plot(widgetfunction)	Generate an interactive plot widget, allowing the user to interact with the SPARC data and the galaxy's components.
on_button_clicked(_)	A function to reset values when the 'Best Fit' button is clicked.
GalaxyImage([position, survey])	Fetch and display an image of the selected galaxy.

ToC: Attributes

textfile	A local text file, opened in read-only mode, indicating a chosen galaxy.
galaxy	The name of the chosen galaxy.
SPARC_file_path	The filename (including relative path) containing data for the chosen galaxy.
data	A numpy array of data loaded from the SPARC file path.
warning_bulge	If the bulge component is missing, a message indicating that it is. Otherwise, an empty string.
warning_disk	If the disk component is missing, a message indicating that it is. Otherwise, an empty string.
warning_gas	If the gas component is missing, a message indicating that it is. Otherwise, an empty string.
distance	Distance to galaxy, in Mpc.
fit_mod	An lmfit Model object for the totalcurve function.
fit_params	An lmfit Parameters object for the fit_mod Model.
fit	An lmfit fitting result for the fit_mod Model against the data imported for the chosen galaxy.
bestfit	Best fit results of the fit of the total curve against the galaxy's data.
fit_dict	Dictionary of best parameter results from the fit of the total curve against the galaxy's data.
bpref	Slider for controlling the bulge prefactor.
dpref	Slider for controlling the disk prefactor.
rc	Slider for controlling the cutoff radius.
rho0	Slider for controlling the halo density variable rho0.
button	A button that returns all settings to the best fit.
out	A handler for widget output.

Members

widget_SPARC.textfile

A local text file, opened in read-only mode, indicating a chosen galaxy.

Type

file

The purpose of this file is to: 1. Allow this chosen galaxy variable to be passed flexibly between programs. 2. Allow this chosen galaxy to be retained between sessions.

See also

The data in this text file is stored in the galaxy variable.

widget_SPARC.galaxy

The name of the chosen galaxy.

Type

string

See also

This string is retrieved from textfile.

widget_SPARC.SPARC_file_path

The filename (including relative path) containing data for the chosen galaxy.

Type

string

widget_SPARC.data

A numpy array of data loaded from the SPARC file path.

Type

array

widget_SPARC.warning_bulge = There is no bulge component.

If the bulge component is missing, a message indicating that it is. Otherwise, an empty string.

Type

string

widget_SPARC.warning_disk = There is no disk component.

If the disk component is missing, a message indicating that it is. Otherwise, an empty string.

Type

string

widget_SPARC.warning_gas = There is no gas component.

If the gas component is missing, a message indicating that it is. Otherwise, an empty string.

Type

string

widget_SPARC.distance

Distance to galaxy, in Mpc.

Type

float

widget_SPARC.bulge(r, bpref)

Interpolating the bulge velocity.

Parameters

r[array]

Sampling radius values or distance from the center of the galaxy (in kpc).

bpref[float]

Bulge prefactor or scaling factor (unitless).

Returns

Splined bulge velocity as a [function] of sampling radii.

Example

>>> # Define measured radius and velocity and interpolate them
>>> import numpy as np
>>> Rad = np.array([0, 0.5, 1.2, 2.6, 5.3, 6.7, 7.1, 9.5])
>>> Vbul = np.array([100, 200, 280, 200, 130, 120, 110, 100])
>>> r = np.linspace(0, 20, 50)
>>> bulgespline = bulge(r, bpref=1)
>>> plt.plot(Rad, Vbul, 'ro')
>>> plt.plot(r, bulgespline)
>>> plt.show()

widget_SPARC.disk(r, dpref)

Interpolating the disk velocity.

Parameters

r[array]

Sampling radius values or distance from the center of the galaxy (in kpc).

dpref[float]

Disk prefactor or scaling factor (unitless).

Returns

Splined disk velocity as a [function] of sampling radii.

Example

>>> # Define measured radius and velocity and interpolate them
>>> #Rad = #Plotting Rad and Vdisk as imported from this library
>>> #Vdisk = #^
>>> r = np.linspace(0, 20, 50)
>>> diskspline = disk(r, dpref=1)
>>> plt.plot(Rad, Vdisk, 'ro')
>>> plt.plot(r, diskspline)
>>> plt.show()

widget_SPARC.gas(r)

Interpolating the gas velocity.

Parameters

r[array]

Sampling radius values or distance from the center of the galaxy (in kpc).

Returns

Splined gas velocity as a [function] of sampling radii.

Example

>>> # Define measured radius and velocity and interpolate them
>>> #Rad = # We plot the radius and velocities as imported from this library.
>>> #Vgas = #^
>>> r = np.linspace(0, 20, 50)
>>> gasspline = gas(r)
>>> plt.plot(Rad, Vgas, 'ro')
>>> plt.plot(r, gasspline)
>>> plt.show()

widget_SPARC.halo(r, rc, rho0)

Function to calculate the gravitational effect of a Dark Matter halo using the isothermal density profile (Source: [Jimenez2003]).

Parameters

r[array]

Radius values or distance from the center of the galaxy used to calculate velocities (in kpc).

rc[float]

Cutoff radius (in kpc). Default: 1.4

rho0[float]

Central mass density (in solar mass/kpc^3). Default: 0.31e9

Returns

A [float] or an [array] of halo velocities (in km/s).

Example

>>> # Calculate the gravitational effect of the Dark Matter halo
>>> # of NGC 5533, 10 kpc away.
>>> print(halo(r=np.array([10,15,20,25,30,35,40,45,50,100]),
...     rc=1.4, rho0=0.31e9)))
[162.0220417  168.23695403 171.41313542 173.33987823 174.63289949
175.5605844  176.25855891 176.80272454 177.23886723 179.21029129]

widget_SPARC.totalcurve(r, bpref, dpref, rc, rho0)

Function to calculate the total gravitational effect of all components of a galaxy. The velocities of each component is added in quadrature to calculate the total rotational velocity.

Parameters

r[array]

Radius values or distance from the center of the galaxy used to calculate velocities (in kpc).

bpref[float]

Bulge prefactor or scaling factor (unitless).

dpref[float]

Disk prefactor or scaling factor (unitless).

rc[float]

Cutoff radius (in kpc).

rho0[float]

Central mass density (in solar mass/kpc^3).

Returns

A [float] or an [array] of total velocities (in km/s).

Note

If the galaxy contains a supermassive black hole at the center, it is incorporated in the bulge velocity.

Example

>>> # Calculate the gravitational effect of all components of a galaxy
>>> #at the distance of 10,15,20,25,30,35,40,45,50, and 100 kpc.
>>> print(totalcurve(r=np.array([10,15,20,25,30,35,40,45,50,100]),
...     bpref=1, dpref=1, rc=1.4, rho0=0.31e9)))
[3.34371479e+02 3.22215072e+02 7.25902496e+02 2.16917607e+03 5.21519130e+03
1.04268198e+04 1.83732304e+04 2.96250118e+04 4.47531137e+04 5.34875631e+05]

widget_SPARC.fit_mod

An lmfit Model object for the totalcurve function.

Type

lmfit.Model

widget_SPARC.fit_params

An lmfit Parameters object for the fit_mod Model.

Type

lmfit.Parameters

Parameter	Starting Value	Minimum	Maximum
rc	1.4	0.1	(None)
rho0	3.10e8	0	(None)
bpref	1	0.5	100
dpref	1	0.5	100

widget_SPARC.fit

An lmfit fitting result for the fit_mod Model against the data imported for the chosen galaxy.

Type

lmfit.ModelResult

widget_SPARC.bestfit

Best fit results of the fit of the total curve against the galaxy's data.

Type

ndarray

widget_SPARC.fit_dict

Dictionary of best parameter results from the fit of the total curve against the galaxy's data.

Type

dict

Keys

bpref, dpref, rc, rho0.

widget_SPARC.widgetfunction(bpref, dpref, rc, rho0)

Generate a plot for use with interactive rotation curve plot of SPARC data with sliders for parameters. Can also be used to generate a static plot of individual components and their total.

Parameters

bpref: [float]

Prefactor scaling the bulge component.

dpref: [float]

Prefactor scaling the disk component.

rcut: [float]

Cutoff radius of the halo.

rho0: [float]

Density parameter for the halo.

Returns

None

See also

For information on how the curves displayed are calculated, see: totalcurve, bulge, disk, halo, gas.

See the interactive_plot function as an example usecase of this function.

widget_SPARC.bpref

Slider for controlling the bulge prefactor.

Type

ipywidgets.widgets.widget_float.FloatSlider

widget_SPARC.dpref

Slider for controlling the disk prefactor.

Type

ipywidgets.widgets.widget_float.FloatSlider

widget_SPARC.rc

Slider for controlling the cutoff radius.

Type

ipywidgets.widgets.widget_float.FloatSlider

widget_SPARC.rho0

Slider for controlling the halo density variable rho0.

Type

ipywidgets.widgets.widget_float.FloatSlider

widget_SPARC.interactive_plot(widgetfunction)

Generate an interactive plot widget, allowing the user to interact with the SPARC data and the galaxy’s components.

Parameters

widgetfunction: [function]

A function that generates the base plot for the widget to alter. This should, in all likelihood, be widgetfunction.

Returns

[ipywidgets.widgets.interaction.interactive] – creates sliders to make the plot interactive.

See also

For an example usage of this function, see the notebook 09_Widget_SPARC_Galaxies.ipynb on Binder.

widget_SPARC.button

A button that returns all settings to the best fit.

Type

ipywidgets.widgets.widget_button.Button

widget_SPARC.out

A handler for widget output.

Type

ipywidgets.widgets.widget_output.Output

widget_SPARC.on_button_clicked(_)

A function to reset values when the ‘Best Fit’ button is clicked.

Parameters

None

Returns

None

Example

>>> button.on_click(on_button_clicked)

This renders the button click behavior seen in 09_Widget_SPARC_Galaxies.ipynb on Binder.

widget_SPARC.GalaxyImage(position=galaxy, survey=['DSS'])

Fetch and display an image of the selected galaxy.

Parameters

Position: [string]

The name of the galaxy whose image is to be fetched.

Survey: [list]

The name(s) of surveys, as strings, containing the galaxy whose image is to be fetched.

Returns

None

See also

For an example usage of this function, see the notebook 09_Widget_SPARC_Galaxies.ipynb on Binder.