Cosmological parameters from the IRAS galaxy sample

An IRAS-selected sample of galaxies is used here to make a dynamical estimate of cosmological parameters. It is assumed that the sample traces the mass density of the universe on scales of 40 Mpc and that the microwave background velocity is gravitationally induced by this mass distribution. Models are fitted to the observed differential flux dipole in order to extrapolate to the true total integrated dipole down to zero flux. Linear perturbation theory allows a value of 1.2 to be inferred for the cosmological density parameter; systematic errors may be as large as 55 percent, however. The bulk of the dipole is generated on scales of 35 + or - 10 Mpc, although this result is fairly model-dependent. The mean density fluctuations on the scale of the dipole are roughly 0.3, in accord with measurements of the two-point correlation function of galaxies. 51 references.