N09¶

class dust_attenuation.shapes.N09(x0=0.2175, gamma=0.035, ampl=0, slope=0.0, Av=1.0, **kwargs)[source]¶

Bases: dust_attenuation.baseclasses.BaseAttAvModel

Attenuation curve using a modified version of the Calzetti law allowing for a varying UV slope and the presence of a UV bump.

Parameters

x0: float: Central wavelength of the UV bump (in microns).
gamma: float: Width (FWHM) of thhe UV bump (in microns).
ampl: float: Amplitude of the UV bump.
slope: float: Slope of the power law.
Av: float: attenuation in V band.

Raises

InputParameterError: Input Av values outside of defined range

Notes

The original formalism is from Noll et al, A&A 507, 1793–1813 (2009).

Example:

import matplotlib.pyplot as plt
import numpy as np
import astropy.units as u

from dust_attenuation.shapes import N09

fig, ax = plt.subplots()

# generate the curves and plot them
x = np.arange(0.5,10,0.1)/u.micron

slopes = [-1, -0.5, 0, 0.5, 1]
for slope in slopes:
    att_model = N09(Av=1,ampl=3.5,slope=slope)
    ax.plot(x,att_model(1/x),label=r'$\delta$ = %.2f' % (slope))

ax.set_xlabel(r'$x$ [$\mu m^{-1}$]')
ax.set_ylabel(r'A(x) [mag]')

ax.legend(loc='best')
plt.title("Noll09 with varying slopes")
plt.show()

(Source code, png, hires.png, pdf)

../_images/dust_attenuation-shapes-N09-1.png

Attributes Summary

`Av`
`Rv_C00`
`ampl`
`gamma`
`param_names`
`slope`
`x0`
`x_range`

Methods Summary

`evaluate`(x, Av, x0, gamma, ampl, slope)	N09 function
`k_lambda`(x, x0, gamma, ampl, slope)	Compute the starburst reddening curve k’(λ)=A(λ)/E(B-V) using recipe of Calzetti 2000 and Leitherer 2002
`power_law`(x, slope)	Power law normalised at 0.55 microns (V band).
`uv_bump`(x, x0, gamma, ampl)	Drude profile for computing the UV bump.

Attributes Documentation

Av = Parameter('Av', value=1.0, bounds=(0.0, None))¶

Rv_C00 = 4.05¶

ampl = Parameter('ampl', value=0.0, bounds=(0, None))¶

gamma = Parameter('gamma', value=0.035, bounds=(0, None))¶

param_names = ('Av', 'x0', 'gamma', 'ampl', 'slope')¶

slope = Parameter('slope', value=0.0, bounds=(-3.0, 3.0))¶

x0 = Parameter('x0', value=0.2175, bounds=(0, None))¶

x_range = [0.097, 2.2]¶

Methods Documentation

evaluate(x, Av, x0, gamma, ampl, slope)[source]¶

N09 function

Parameters

x: np array (float): expects either x in units of wavelengths or frequency or assumes wavelengths in [micron] internally microns are used
Av: float: attenuation in V band.
x0: float: Central wavelength of the UV bump (in microns).
gamma: float: Width (FWHM) of thhe UV bump (in microns).
ampl: float: Amplitude of the UV bump.
slope: float: Slope of the power law.

Returns

att: np array (float): Att(x) attenuation curve [mag]

Raises

ValueError: Input x values outside of defined range

k_lambda(x, x0, gamma, ampl, slope)[source]¶

Compute the starburst reddening curve k’(λ)=A(λ)/E(B-V) using recipe of Calzetti 2000 and Leitherer 2002

Parameters

in_x: np array (float): expects either x in units of wavelengths or frequency or assumes wavelengths in [micron] internally microns are used
x0: float: Central wavelength of the UV bump (in microns).
gamma: float: Width (FWHM) of thhe UV bump (in microns).
ampl: float: Amplitude of the UV bump.
slope: float: Slope of the power law.

Returns

k_lambda: np array (float): k_lambda(x) reddening curve

Raises

ValueError: Input x values outside of defined range

power_law(x, slope)[source]¶

Power law normalised at 0.55 microns (V band).

Parameters

x: np array (float): expects wavelengths in [micron]
slope: float: slope of the power law

Returns

powlaw: np array (float): power law

uv_bump(x, x0, gamma, ampl)[source]¶

Drude profile for computing the UV bump.

Parameters

x: np array (float): expects wavelengths in [micron]
x0: float: Central wavelength of the UV bump (in microns).
gamma: float: Width (FWHM) of the UV bump (in microns).
ampl: float: Amplitude of the UV bump.

Returns

np array (float): lorentzian-like Drude profile

Raises

ValueError: Input x values outside of defined range

Navigation

N09¶