The Velocity Field from Type Ia Supernovae Matches the Gravity Field from Galaxy Surveys

Abstract

We compare the peculiar velocities of nearby Type la supernovae (SNs) with those predicted by the gravity fields of full-sky galaxy catalogs. The method provides a powerful test of the gravitational instability paradigm and strong constraints on the density parameter beta = Omega(0.6)/b. For 24 Type Ia SNs within 10,000 km s(-1), we find that the observed Type Ia SN peculiar velocities are well modeled by the predictions derived from the 1.2 Jy IRAS survey and the Optical Redshift Survey (ORS). Our best beta value is 0.4 from IRAS, and 0.3 from the ORS, with beta>0.7 and beta<0.15 ruled out at 95% confidence levels from the IRAS comparison. Bootstrap resampling tests show these results to be robust in the mean and in its error. The precision of this technique will improve as additional nearby Type Ia SNs are discovered and monitored.