Model Flavors¶
There are three different types of models: averages, radiative transfer based, and shape fitting.
Average models¶
These models provide averages from the literature with the ability to interpolate between the observed data points. In general, these average models have shapes that are not dependent on the amount of dust.
The C00 average attenuation model is based on a small number of
starburst galaxies observed
in the ultraviolet with the International Ultraviolet Explorer (IUE)
supplemented with ground-based optical spectroscopy,
near-infrared photometry, and
Infrared Space Observatory (ISO) far-infrared photometry
(Calzetti et al. 2000).
(Source code, png, hires.png, pdf)
Radiative Transfer Based Models¶
These models provide attenuation predictions based on dust radiative transfer calculations. The attenuation curve strength and wavelength dependent shape are based on the amount of dust, star/dust geometry, and other parameters.
Witt & Gordon 2000 (WG00)¶
The WG00 attenuation models are based on DIRTY radiative transfer
calculations for spherical galactic environments (shell, dusty, cloudy)
with homogeneous or clumpy local dust distributions using
empirical Milky Way (MW) and Small Magellanic Cloud (SMC)
dust grain properties (Witt & Gordon 2000).
The WG00 models were chosen to span the range of
possible star/dust geometries and types of dust grains.
Example WG00 models showing variation in shape with amount of dust.
(Source code, png, hires.png, pdf)
Example WG00 models showing shape variation with different types of
dust grains.
(Source code, png, hires.png, pdf)
Example WG00 models showing shape variation with different spherical galactic
environments.
(Source code, png, hires.png, pdf)
Example WG00 models showing shape variation with local dust distributions.
(Source code, png, hires.png, pdf)
Shape fitting models¶
These models allow for more arbitrary shapes to be modeled than the other model flavors.
N09: modified Calzetti law from Noll et al. 2009¶
Noll+09 first introduced a modified version of the C00 law, allowing
for a varying slope and the presence of a UV bump.
Example N09 models showing variation in slopes.
A UV bump with an amplitude of 3.5 is added to the C00 law.
(Source code, png, hires.png, pdf)
Example N09 models showing variation in UV bump amplitude.
The central wavelength of the UV bump and its width are kept fixed
to 0.2175 and 0.035 microns respectively.
(Source code, png, hires.png, pdf)
SBL18: modified version of N09¶
N09 first introduced a modified version of the C00 law, allowing
for a varying slope and the presence of a UV bump. In the original formalism,
the UV bump is affected by the power law. In the SBL18 class the UV bump is added
to the attenuation law after applying the power law.
Example comparing variation in UV bump strength for N09 and SBL18 models.
The slope is fixed to -0.5. Continuous and dashed lines are for N09 and SBL18 respectively.
The UV bump amplitude of N09 is stronger than SBL18.
(Source code, png, hires.png, pdf)
The slope is now fixed to 0.5. Continuous and dashed lines are for N09 and SBL18 respectively.
The UV bump amplitude of N09 is now weaker than SBL18.
(Source code, png, hires.png, pdf)
