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

Understand

Peculiar velocity measurements are the only tool available in the low-redshift Universe for mapping 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 Mpc/h, 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 $\beta^* \equiv \Omega_{\rm{m}}^{0.55}/b^* = 0.431 \pm 0.021$, suggesting $\Omega_{\rm{m}}^{0.55}\sigma_{\rm{8,lin}} = 0.401 \pm 0.024$, in good agreement with other probes.