From: Alex Kim (agkim@lbl.gov)
Date: Sun Apr 27 2003 - 09:37:27 PDT
Here are the results of the Monte Carlo run by Ramon Miquel on the
effect of an extreme evolution in dust extinction properties on
comsological parameter determination.
> Possible evolution in the extinction properties of host-galaxy dust is
> a source of systematic error in our measurement. To examine the size
> of the effect, we consider an extreme situation where dust in $z <
> 0.3$ spiral galaxies have a Cardelli, Clayton, and Mathis $R_V=3.1$
> law whereas higher-redshift galaxy dust have $R_V=1.505$. We use the
> Monte Carlo described in Kim et al. (2003) to study the bias induced
> when an $R_V=3.1$ extinction correction is unappropriately applied to
> all supernovae. We incorperate the redshift and $E(B-V)$
> distributions of the supernovae considered in this paper and an
> $E(B-V) < 0.1$ cut is applied. For an input cosmology of
> $\Omega_M=0.3$ and $\Omega_\Lambda=0.7$, we find a modest shift in
> the cosmological parameters to $\Omega_M=0.34$ and
> $\Omega_\Lambda=0.67$ without assuming a flat universe.
>
> This bias moves almost exactly along the line
> $\Omega_M+\Omega_\Lambda=1$, increasing uncertainty along the thin
> axis of the error contour, and hence also in the deceleration
> parameter. However, the extreme difference in dust properties
> considered in the Monte Carlo contributes a shift in the cosmological
> parameters that is less than 1 $\sigma$ of our quoted statistical
> error bars.
>
> Kim, Linder, Miquel, & Mostek (2003) MNRAS, submitted
>
> Acknowledgements add Ramon Miquel.
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