The Velocity Field of the Local Universe from Measurements of Type Ia Supernovae

We present a measurement of the velocity flow of the local universe relative to the CMB rest frame, based on the recent Jha et al. sample of 133 low-redshift Type Ia supernovae. At a depth of 4500 km s-1 we find a dipole amplitude of 279 ± 68 km s-1 in the direction l = 285° ± 18°, b = -10° ± 15°, consistent with earlier measurements and with the assumption that the local velocity field is dominated by the Great Attractor region. At a greater depth of 5900 km s-1, we find a shift in the dipole direction toward the Shapley Concentration. We also present the first measurement of the quadrupole term in the local velocity flow at these depths. Finally, we have performed detailed studies based on N-body simulations of the expected precision with which the lowest multipoles in the velocity field can be measured out to redshifts of order 0.1. Our mock catalogs are in good agreement with current observations and demonstrate that our results are robust with respect to assumptions about the influence of local environment on the Type Ia supernova rate.