Open AccessPeculiar velocities and the mean density parameter
Author(s) -
Padilla Nelson,
Lambas Diego G.
Publication year - 1999
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.1999.02914.x
Subject(s) - physics , astrophysics , galaxy , peculiar velocity , tully–fisher relation , cosmic variance , redshift , dark matter , correlation function (quantum field theory) , cosmic cancer database , galaxy formation and evolution , galaxy rotation curve , quantum mechanics , dielectric
We study the peculiar velocity field inferred from the Mark III spirals using a new method of analysis. We estimate optimal values of Tully–Fisher scatter and zero‐point offset, and we derive the three‐dimensional rms peculiar velocity ( σ v ) of the galaxies in the samples analysed. We check our statistical analysis using mock catalogues derived from numerical simulations of cold dark matter (CDM) models considering measurement uncertainties and sampling variations. Our best determination for the observations is σ v =(660±50) km s −1 . We use the linear theory relation between σ v , the density parameter Ω, and the galaxy correlation function ξ ( r ) to infer the quantity , where b is the linear bias parameter of optical galaxies and the uncertainties correspond to bootstrap resampling and an estimated cosmic variance added in quadrature. Our findings are consistent with the results of cluster abundances and redshift‐space distortion of the two‐point correlation function. These statistical measurements suggest a low value of the density parameter Ω∼0.4 if optical galaxies are not strongly biased tracers of mass.