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 ellipticals , and Tully-Fisher distances to spirals .
The three peculiar velocity samples are each in good agreement with the predicted velocities and produce consistent results for \beta _ { K } = \Omega _ { \mathrm { m } } ^ { 0.6 } / b _ { K } .
Taken together the best fit \beta _ { K } = 0.49 \pm 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 both samples are equally good tracers of the underlying dark matter distribution , but that early-types are more clustered by a relative factor b _ { \mathrm { E } } / b _ { \mathrm { S } } \sim 1.6 .
The density fluctuations of 2MASS galaxies in 8 h ^ { -1 } Mpc spheres in the local volume is found to be \sigma _ { \mathrm { 8 ,K } } = 0.9 .
From this result and our value of \beta _ { K } , we find \sigma _ { 8 } ( \Omega _ { \mathrm { m } } / 0.3 ) ^ { 0.6 } = 0.91 \pm 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 _ { \mathrm { m } } / 0.3 ) ^ { 0.6 } = 0.85 \pm 0.05 .