Cosmological parameters from the comparison of the 2MASS gravity field with peculiar velocity surveys

We compare the peculiar velocity field within 65 h(-1) Mpc predicted from 2MASS photometry and public redshift data to three independent peculiar velocity surveys based on Type Ia supernovae, surface brightness fluctuations in elliptical galaxies, and Tully-Fisher distances to spiral galaxies. The three peculiar velocity samples are each in good agreement with the predicted velocities and produce consistent results for beta(K) = Omega(0.6)(m)/b(K) . Taken together, the best-fit beta(K) = 0.49 +/- 0.04. We explore the effects of morphology on the determination of beta by splitting the 2MASS sample into E+S0 and S+Irr density fields and find that both samples are equally good tracers of the underlying dark matter distribution, but that early types are more clustered, by a relative factor b(E)/b(S) similar to 1.6. The density fluctuations of 2MASS galaxies in 8 h(-1) Mpc spheres in the local volume is found to be sigma(8.K) = 0.9. From this result and our value of beta(K), we find sigma(8)(Omega(m)/0.3)(0.6) = 0.91 +/- 0.12. This is in excellent agreement with results from the IRAS redshift surveys, as well as other cosmological probes. Combining the 2MASS and IRAS peculiar velocity results yields sigma(8)(Omega(m)/0.3)(0.6) = 0.85 +/- 0.05.