Constraints on Omega from the IRAS redshift surveys

摘要: We measure the anisotropy of redshift-space power spectrum in 1.2-Jy and QDOT redshift surveys IRAS-selected galaxies. On large scales, this is caused by coherent peculiar motions, gravitational instability theory predicts a distortion that depends only on ratio $\beta \equiv f(\Omega)/b \approx \Omega^{0.6}/b$, where Omega cosmological density parameter $b$ bias parameter. small dominated random velocity dispersion non-linear structures. fit observed with an analytic model incorporates two parameters, beta, small-scale sigma_v. Tests N-body simulations show recovers beta quite accurately scales accessible to existing IRAS surveys. Applying our procedure surveys, we find beta=0.52 +/- 0.13 beta=0.54 0.3, respectively. These results imply approximately 0.35 if galaxies trace mass, or factor about 2 Omega=1.