synthesizer.emission_models.transformers.dust_attenuation

A module containing dust attenuation functionality.

This module contains classes for dust attenuation laws. These classes provide a way to calculate the optical depth and transmission curves for a given dust model.

Example usage:

# Create a power law dust model with a slope of -1.0
dust_model = PowerLaw(slope=-1.0)

# Calculate the transmission curve
transmission = dust_model.get_transmission(
    0.33, np.linspace(1000, 10000, 1000)
)

Functions

synthesizer.emission_models.transformers.dust_attenuation.Li08(lam, UV_slope, OPT_NIR_slope, FUV_slope, bump, model)[source]

Drude-like parametric expression for the attenuation curve from Li+08.

Parameters:

  • lam (np.ndarray of float) – The wavelengths (AA units) at which to calculate transmission.

  • UV_slope (float) – Dimensionless parameter describing the UV-FUV slope

  • OPT_NIR_slope (float) – Dimensionless parameter describing the optical/NIR slope

  • FUV_slope (float) – Dimensionless parameter describing the FUV slope

  • bump (float) – Dimensionless parameter describing the UV bump strength (0< bump <1)

  • model (str) – Via this parameter one can choose one of the templates for extinction/attenuation curves from: Calzetti, SMC, MW (R_V=3.1), and LMC

Returns:

tau/tau_v at each input wavelength (lam)

Return type:

np.ndarray of float/float

synthesizer.emission_models.transformers.dust_attenuation.N09Tau(lam, slope, cent_lam, ampl, gamma)[source]

Generate the transmission curve for the Noll+2009 attenuation curve.

Attenuation curve using a modified version of the Calzetti attenuation (Calzetti+2000) law allowing for a varying UV slope and the presence of a UV bump; from Noll+2009

References

https://ui.adsabs.harvard.edu/abs/2009A%26A…499…69N

Parameters:

  • lam (np.ndarray of float) – The input wavelength array (expected in AA units, global unit).

  • slope (float) – The slope of the attenuation curve.

  • cent_lam (float) – The central wavelength of the UV bump, expected in AA.

  • ampl (float) – The amplitude of the UV-bump.

  • gamma (float) – The width (FWHM) of the UV bump, in AA.

Returns:

V-band normalised optical depth for

given wavelength

Return type:

np.ndarray of float

Classes

class synthesizer.emission_models.transformers.dust_attenuation.AttenuationLaw(description, required_params=('tau_v',))[source]

The base class for all attenuation laws.

A child of this class should define it’s own get_tau method with any model specific behaviours. This will be used by get_transmission (which itself can be overloaded by the child if needed).

description

A description of the type of model. Defined on children classes.

Type:

str

required_params

The name of any required parameters needed by the transformer when transforming an emission. These should either be available from an emitter or from the EmissionModel itself. If they are missing an exception will be raised.

Type:

tuple

get_tau(*args)[source]

Compute the V-band normalised optical depth.

get_tau_at_lam(*args)[source]

Compute the optical depth at wavelength.

get_transmission(tau_v, lam, **dust_curve_kwargs)[source]

Compute the transmission curve.

Returns the transmitted flux/luminosity fraction based on an optical depth at a range of wavelengths.

Parameters:

  • tau_v (float/np.ndarray of float) – Optical depth in the V-band. Can either be a single float or array.

  • lam (np.ndarray of float) – The wavelengths (with units) at which to calculate transmission.

  • **dust_curve_kwargs (dict) – Additional keyword arguments to be passed to the dust curve which have been defined on the emitter or model.

Returns:

The transmission at each wavelength. Either (lam.size,) in shape for singular tau_v values or (tau_v.size, lam.size) tau_v is an array.

Return type:

np.ndarray of float

plot_attenuation(lam, fig=None, ax=None, label=None, figsize=(8, 6), show=True, **kwargs)[source]

Plot the attenuation curve.

Parameters:

  • lam (np.ndarray of float) – The wavelengths (with units) at which to calculate transmission.

  • fig (matplotlib.figure.Figure) – The figure to plot on. If None, a new figure will be created.

  • ax (matplotlib.axes.Axes) – The axis to plot on. If None, a new axis will be created.

  • label (str) – The label to use for the plot.

  • figsize (tuple) – The size of the figure to create if fig is None.

  • show (bool) – Whether to show the plot.

  • **kwargs (dict) – Keyword arguments to be provided to the plot call.

Returns:

The figure and axis objects.

Return type:

fig, ax

plot_transmission(tau_v, lam, fig=None, ax=None, label=None, figsize=(8, 6), show=True)[source]

Plot the transmission curve.

Parameters:

  • tau_v (float/np.ndarray of float) – Optical depth in the V-band. Can either be a single float or array.

  • lam (np.ndarray of float) – The wavelengths (with units) at which to calculate transmission.

  • fig (matplotlib.figure.Figure) – The figure to plot on. If None, a new figure will be created.

  • ax (matplotlib.axes.Axes) – The axis to plot on. If None, a new axis will be created.

  • label (str) – The label to use for the plot.

  • figsize (tuple) – The size of the figure to create if fig is None.

  • show (bool) – Whether to show the plot.

Returns:

The figure and axis objects.

Return type:

fig, ax

Examples using synthesizer.emission_models.transformers.dust_attenuation.AttenuationLaw

Camels example

Camels example

SC-SAM example

SC-SAM example

Photometry example

Photometry example

Generating Lines from a Parametric Galaxy

Generating Lines from a Parametric Galaxy

Generate parametric observed SED

Generate parametric observed SED

An example showing how to scale a galaxy’s mass by luminosity/flux.

An example showing how to scale a galaxy's mass by luminosity/flux.

Generate parametric galaxy SED

Generate parametric galaxy SED

Plot line of sight diagnostics

Plot line of sight diagnostics
class synthesizer.emission_models.transformers.dust_attenuation.Calzetti2000(slope=0, cent_lam=unyt_quantity(2175, 'Å'), ampl=0, gamma=unyt_quantity(350, 'Å'))[source]

Calzetti attenuation curve.

This includes options for the slope and UV-bump implemented in Noll et al. 2009.

slope

The slope of the attenuation curve.

Type:

float

cent_lam

The central wavelength of the UV bump, expected in AA.

Type:

float

ampl

The amplitude of the UV-bump.

Type:

float

gamma

The width (FWHM) of the UV bump, in AA.

Type:

float

get_tau(lam)[source]

Calculate V-band normalised optical depth.

(Uses the N09Tau function defined above.)

Parameters:

lam (float/np.ndarray of float) – An array of wavelengths or a single wavlength at which to calculate optical depths (in AA, global unit).

Returns:

The V-band noramlised optical depth.

Return type:

float/array-like, float

get_tau_at_lam(lam)[source]

Calculate optical depth at a wavelength.

(Uses the N09Tau function defined above.)

Parameters:

lam (float/array-like, float) – An array of wavelengths or a single wavlength at which to calculate optical depths (in AA, global unit).

Returns:

float/array-like, float

The optical depth.

class synthesizer.emission_models.transformers.dust_attenuation.GrainsWD01(model='SMCBar')[source]

Weingarter and Draine 2001 dust grain extinction model.

Includes curves for MW, SMC and LMC or any available in WD01.

model

The dust grain model used.

Type:

str

emodel

The function that describes the model from WD01 imported above.

Type:

function

get_tau(lam, interp='slinear')[source]

Calculate V-band normalised optical depth.

Parameters:

  • lam (float/np.ndarray of float) – An array of wavelengths or a single wavlength at which to calculate optical depths (in AA, global unit).

  • interp (str) – The type of interpolation to use. Can be ‘linear’, ‘nearest’, ‘nearest-up’, ‘zero’, ‘slinear’, ‘quadratic’, ‘cubic’, ‘previous’, or ‘next’. ‘zero’, ‘slinear’, ‘quadratic’ and ‘cubic’ refer to a spline interpolation of zeroth, first, second or third order. Uses scipy.interpolate.interp1d.

Returns:

The optical depth.

Return type:

float/np.ndarray of float

get_tau_at_lam(lam, interp='slinear')[source]

Calculate optical depth at a wavelength.

Parameters:

  • lam (float/array-like, float) – An array of wavelengths or a single wavlength at which to calculate optical depths (in AA, global unit).

  • interp (str) – The type of interpolation to use. Can be ‘linear’, ‘nearest’, ‘nearest-up’, ‘zero’, ‘slinear’, ‘quadratic’, ‘cubic’, ‘previous’, or ‘next’. ‘zero’, ‘slinear’, ‘quadratic’ and ‘cubic’ refer to a spline interpolation of zeroth, first, second or third order. Uses scipy.interpolate.interp1d.

Returns:

float/array-like, float

The optical depth.

class synthesizer.emission_models.transformers.dust_attenuation.MWN18[source]

Milky Way attenuation curve used in Narayanan+2018.

data

The data describing the dust curve, loaded from MW_N18.npz.

Type:

np.ndarray of float

tau_lam_v

The V band optical depth.

Type:

float

get_tau(lam, interp='cubic')[source]

Calculate V-band normalised optical depth.

Parameters:

  • lam (float/array, float) – An array of wavelengths or a single wavlength at which to calculate optical depths (in AA, global unit).

  • interp (str) – The type of interpolation to use. Can be ‘linear’, ‘nearest’, ‘nearest-up’, ‘zero’, ‘slinear’, ‘quadratic’, ‘cubic’, ‘previous’, or ‘next’. ‘zero’, ‘slinear’, ‘quadratic’ and ‘cubic’ refer to a spline interpolation of zeroth, first, second or third order. Uses scipy.interpolate.interp1d.

Returns:

The optical depth.

Return type:

float/array, float

get_tau_at_lam(lam, interp='cubic')[source]

Calculate the optical depth at a wavelength.

Parameters:

  • lam (float/array, float) – An array of wavelengths or a single wavlength at which to calculate optical depths (in AA, global unit).

  • interp (str) – The type of interpolation to use. Can be ‘linear’, ‘nearest’, ‘nearest-up’, ‘zero’, ‘slinear’, ‘quadratic’, ‘cubic’, ‘previous’, or ‘next’. ‘zero’, ‘slinear’, ‘quadratic’ and ‘cubic’ refer to a spline interpolation of zeroth, first, second or third order. Uses scipy.interpolate.interp1d.

Returns:

float/array, float

The optical depth.

class synthesizer.emission_models.transformers.dust_attenuation.ParametricLi08(UV_slope=44.9, OPT_NIR_slope=7.56, FUV_slope=61.2, bump=0.0, model='Calzetti')[source]

Parametric, empirical attenuation curve.

Implemented in Li+08, Evolution of the parameters up to high-z (z=12) studied in: Markov+23a,b

UV_slope

Dimensionless parameter describing the UV-FUV slope (0, 50)

Type:

float

OPT_NIR_slope

Dimensionless parameter describing the optical/NIR slope (0, 10)

Type:

float

FUV_slope

Dimensionless parameter describing the FUV slope (-1, 75)

Type:

float

bump

Dimensionless parameter describing the UV bump strength (-0.005< bump <0.06)

Type:

float

model

Fixing attenuation/extinction curve to one of the known templates: MW, SMC, LMC, Calzetti

Type:

str

get_tau(lam)[source]

Calculate V-band normalised optical depth.

(Uses the Li_08 function defined above.)

Parameters:

lam (float/np.ndarray of float) – An array of wavelengths or a single wavlength at which to calculate optical depths (in AA, global unit).

Returns:

The V-band normalised optical depth.

Return type:

float/array-like, float

get_tau_at_lam(lam)[source]

Calculate optical depth at a wavelength.

(Uses the Li_08 function defined above.)

Parameters:

lam (float/array-like, float) – An array of wavelengths or a single wavlength at which to calculate optical depths (in AA, global unit).

Returns:

float/array-like, float

The optical depth.

class synthesizer.emission_models.transformers.dust_attenuation.PowerLaw(slope=-1.0)[source]

Custom power law dust curve.

slope

The slope of the power law.

Type:

float

get_tau(lam)[source]

Calculate V-band normalised optical depth.

Parameters:

lam (float/np.ndarray of float) – An array of wavelengths or a single wavlength at which to calculate optical depths.

Returns:

The optical depth.

Return type:

float/np.ndarray of float

get_tau_at_lam(lam)[source]

Calculate optical depth at a wavelength.

Parameters:

lam (float/np.ndarray of float) – An array of wavelengths or a single wavlength at which to calculate optical depths.

Returns:

The optical depth.

Return type:

float/np.ndarray of float