Preliminary exploration of the impact of host galaxy dust on cosmological parameters

We present preliminary analysis and considerations of the impact of dust on the measurement of cosmological parameters based on Type Ia supernovae. This analysis relies on the models of Commins [this proceedings, 2003] and employs subtraction of median extinction values from the measured magnitudes of Type Ia supernovae found in spiral galaxies, but combined with observational selection effects. Then, we estimate corrections to cosmological parameters. This work generally supports the SCP and Hi-Z team discovery of a non-zero Λ. One of the goals of some of the dust treatments was to find a solution to the dust corrections that could “re-center” the fit to cosmological parameters from supernovae on the Ωtot=1 line segment in the Ωm−ΩΛ plane. Such a “solution” was found and requires more dust in distant SCP cosmological supernovae than in nearby galaxies (the Calan–Tololo supernovae). Other host galaxy dust scenarios with differing amounts of dust and consequences for cosmology are explored. No convincing scenario of dust has yet been able to be developed for host galaxies in the observed SCP data which include observational selection that yields a Λ=0 universe.