Diverse reddening distributions in sight lines to type Ia supernovae

Understand

Precise cosmological constraints from type Ia supernovae require adequately accurate corrections for host-galaxy extinction.

• Modelling these corrections is challenged by the problem of disentangling supernova intrinsic colours from host-galaxy interstellar reddening.
• The latter is commonly modelled in a probabilistic way assuming an exponential distribution exp(-E(B-V)/\tau) as a universal prior which is applied across all types of supernova host galaxies.
• We test the robustness of the exponential model and its universality against predictions based on simulating dust and type Ia supernova distributions in host galaxies of different morphological types.