Cosmological parameters from the comparison of peculiar velocities with predictions from the 2M++ density field

Peculiar velocity measurements are the only tool available in the low-redshift Universe formapping the large-scale distribution of matter and can thus be used to constrain cosmology. Using redshifts from the 2M++ redshift compilation, we reconstruct the density of galaxies within 200 h(-1) Mpc, allowing for the first time good sampling of important superclusters such as the Shapley Concentration. We compare the predicted peculiar velocities from 2M++ to Tully-Fisher and SNe peculiar velocities. We find a value of beta* equivalent to Omega (0.55)(m)/b* = 0.431 +/- 0.021, suggesting Omega(0.55)(m)sigma 8,lin = 0.401 +/- 0.024, in good agreement with other probes. The predicted peculiar velocity of the Local Group arising from the 2M++ volume alone is 540 +/- 40 km s(-1), towards l = 268 degrees +/- 4 degrees, b = 38 degrees +/- 6 degrees, only 10 degrees out of alignment with the cosmic microwave background dipole. To account for velocity contributions arising from sources outside the 2M++ volume, we fit simultaneously for beta* and an external bulk flow in our analysis. We find that an external bulk flow is preferred at the 5.1 sigma level, and the best fit has a velocity of 159 +/- 23 km s(-1) towards l = 304 degrees +/- 11 degrees, b = 6 degrees +/- 13 degrees. Finally, the predicted bulk flow of a 50 h(-1) Mpc Gaussian-weighted volume centred on the Local Group is 230 +/- 30 km s(-1), in the direction l = 293 degrees +/- 8 degrees, b = 14 degrees +/- 10 degrees, in agreement with predictions from Lambda cold dark matter.