2005/11/01 by R. W. Pike, Michael J. Hudson · 2 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Cosmology and Gravitation Theories #Galaxies: Formation, Evolution, Phenomena #astro-ph
paper · pdf · doi:10.1086/497359
published as Astrophys.J. 635 (2005) 11-21 · 11 pages, ApJ accepted
arxiv created 2005/11/01 · openalex publication_date 2005/12/06 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
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 βK=Ω\sbrm0.6/bK. Taken together the best fit βK = 0.49 ± 0.04. We explore the effects of morphology on the determination of β 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\sbrE/b\sbrS ∼ 1.6. The density fluctuations of 2MASS galaxies in 8 h-1 Mpc spheres in the local volume is found to be σ\sbr8,K = 0.9. From this result and our value of βK, we find σ8 (Ω\sbrm/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 σ8 (Ω\sbrm^/0.3)0.6 = 0.85±0.05.