N09¶

class dust_attenuation.shapes.N09[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('$x$ [$\mu m^{-1}$]')
ax.set_ylabel('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`	Av: attenuation in V band
`Rv_C00`
`ampl`	bump: amplitude
`gamma`	bump: width (FWHM)
`param_names`
`slope`	slope: slope of the power law
`x0`	bump: centroid
`x_range`

Methods Summary

`evaluate`(x, x0, gamma, ampl, slope, Av)	C00 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¶: Av: attenuation in V band

Rv_C00 = 4.05¶

ampl¶: bump: amplitude

gamma¶: bump: width (FWHM)

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

slope¶: slope: slope of the power law

x0¶: bump: centroid

x_range = [0.097, 2.2]¶

Methods Documentation

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

C00 function

Parameters:	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. Av: float attenuation in V band.
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¶