paper

Cosmological Parameters from the Comparison of the 2MASS Gravity Field with Peculiar Velocity Surveys

arXiv:astro-ph/0511012 · doi:10.1086/497359

Abstract

We compare the peculiar velocity field within 65 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 $β_{K}=Ω\sbr{m}^{0.6}/b_{K}$. Taken together the best fit . We explore the effects of morphology on the determination of 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 $b\sbr{E}/b\sbr{S} \sim 1.6$. The density fluctuations of 2MASS galaxies in Mpc spheres in the local volume is found to be $σ\sbr{8,K} = 0.9$. From this result and our value of , we find $σ_8 (Ω\sbr{m}/0.3)^{0.6} = 0.91\pm0.12$. 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 $σ_8 (Ω\sbr{m}^/0.3)^{0.6} = 0.85\pm0.05$.

11 pages, ApJ accepted

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