A comparison of local Type Ia supernovae with the IRAS PSCz gravity field

We compare the measured peculiar velocities of 98 local (< 150 h -1 Mpc) Type Ia supernovae with predictions derived from the IRAS PSCz survey. There is excellent agreement between the two data sets, with a best-fitting β I (= Ω 0.6 m /b I ) of 0.55 ± 0.06. Subsets of the supernovae data set are further analysed, and the above result is found to be robust with respect to culls by distance, host-galaxy extinction and choice of reference frame in which the analysis is carried out. Alternative methods of determining β I including density-density comparisons, dipole measurements and WMAP-based results are also discussed. We conclude that most recent determinations are consistent with a value of β I = 0.5.