The Galactic extinction

As we saw in chapter 2 , we have a good knowledge of the quantity of Galactique dust according to the direction of observation. This allows us in particular, knowing the laws of extinction to correct for this absorption.

We thus used the extinction law defined by equation 2.33 for the standardization given by Cardelli1989. The values of $E(b-v)$ were given by using the charts of dust presented in schlegel1998. We used the code developed by these authors to determine the values of excess of color.

To take into account Galactic absorption, we simply modified our effective filter by adding this contribution:

$$T'_{eff}(\lambda) = T_{eff}(\lambda) T_{Gal}$$ (9.4)

While using, the extinction law in magnitude 2.34 , we have while passing in flux:

$$T_{Gal} = 10^{-0.4 f(\lambda) E(B-V)}$$ (9.5)

It is checked that for a null excess of color, the transmission is 1.

Figure 9.5 shows the law this extinction law for typical values of $E(b-v)$.

Figure 9.5: Galactic extinction law for typical values of $E(b-v)$

We have from now on a model which enables us to simulate fluxes of supernova for a redshift, a Galactique absorption and a given filter.