Friday, July 5, 2013

1307.1155 (Miguel Quartin et al.)

Accurate Weak Lensing of Standard Candles, Part 2: Measuring sigma8 with Supernovae    [PDF]

Miguel Quartin, Valerio Marra, Luca Amendola
Soon the number of type Ia supernova (SN) measurements should exceed 100,000. Understanding the effect of weak lensing by matter structures on the supernova brightness will then be more important than ever. Although SN lensing is usually seen as a source of systematic noise, we will show that it can be in fact turned into signal. More precisely, the non-Gaussianity introduced by lensing in the SN Hubble diagram dispersion depends rather sensitively on the amplitude sigma8 of the matter power spectrum. By exploiting this relation, we are able to predict constraints on sigma8 of 7% (3%) for a catalog of 100,000 (500,000) SNe of average magnitude error 0.12 without having to assume that such intrinsic dispersion is known a priori. This method is independent of and complementary to the standard methods based on CMB, cosmic shear or cluster abundance observables.
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