synthesizer.emission_models.attenuation.dust

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.attenuation.dust.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 (array-like, float) – The wavelengths (microns 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 (string) – 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)

synthesizer.emission_models.attenuation.dust.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

Parameters:

  • lam (array-like, 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 microns.

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

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

Returns:

(array-like, float)

V-band normalised optical depth for given wavelength

Classes

class synthesizer.emission_models.attenuation.dust.AttenuationLaw(description)[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

get_tau(*args)[source]

Compute the optical depth.

get_transmission(tau_v, lam)[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/array-like, float) – Optical depth in the V-band. Can either be a single float or array.

  • lam (array-like, float) – The wavelengths (with units) at which to calculate transmission.

Returns:

array-like

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.

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

Plot the attenuation curve.

Parameters:

  • lam (array-like, 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:

fig, ax

The figure and axis objects.

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/array-like, float) – Optical depth in the V-band. Can either be a single float or array.

  • lam (array-like, 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:

fig, ax

The figure and axis objects.

Examples using synthesizer.emission_models.attenuation.dust.AttenuationLaw

SC-SAM example

SC-SAM example

Camels example

Camels 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.attenuation.dust.Calzetti2000(slope=0, cent_lam=unyt_quantity(0.2175, 'μm'), ampl=0, gamma=unyt_quantity(0.035, 'μm'))[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 microns.

Type:

float

ampl

The amplitude of the UV-bump.

Type:

float

gamma

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

Type:

float

get_tau(lam)[source]

Calculate V-band normalised optical depth.

(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.attenuation.dust.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)[source]

Calculate V-band normalised optical depth.

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.

get_transmission(tau_v, lam)[source]

Return the transmitted flux/luminosity fraction.

Parameters:

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

  • lam (array-like, float) – The wavelengths (with units) at which to calculate transmission.

Returns:

array-like

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.

class synthesizer.emission_models.attenuation.dust.MWN18[source]

Milky Way attenuation curve used in Narayanan+2018.

data

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

Type:

array-like, 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:

float/array, float

The optical depth.

class synthesizer.emission_models.attenuation.dust.ParametricLi08(UV_slope=1.0, OPT_NIR_slope=1.0, FUV_slope=1.0, bump=0.0, model=None)[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

Type:

float

OPT_NIR_slope

Dimensionless parameter describing the optical/NIR slope

Type:

float

FUV_slope

Dimensionless parameter describing the FUV slope

Type:

float

bump

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

Type:

float

model

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

Type:

string

get_tau(lam)[source]

Calculate V-band normalised optical depth.

(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.attenuation.dust.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/array-like, float) – An array of wavelengths or a single wavlength at which to calculate optical depths.

Returns:

float/array-like, float

The optical depth.

get_tau_at_lam(lam)[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.

Returns:

float/array-like, float

The optical depth.