THE REAL-SPACE POWER SPECTRUM OF IRAS GALAXIES ON LARGE SCALES AND THE REDSHIFT DISTORTION

Galaxy redshift surveys contain valuable cosmological information on t he power spectrum of galaxy clustering, but the information is not eas ily obtained because of distortion of the map arising from the use of redshift as a distance indicator. The distortion arises because of pec uliar velocities, the magnitude of which depends on the mean density o f the Universe. Using a spherical transform of the data which correctl y accounts for the radial nature of the distortion, we calculate simul taneously the real-space power spectrum and the distortion, for the ne ar-all-sky Infrared Astronomical Satellite (IRAS) 1.2-Jy survey. For t he distortion, we find beta = 1.04 +/- 0.3, where beta = Omega(0)(0.6) /b, and b is the IRAS linear bias parameter. We constrain the power sp ectrum on large scales with wavenumbers 0.01 less than or similar to k less than or similar to 0.1 h Mpc(-1), where the 'distant-observer' F ourier approximation should not be used. Power is not convincingly det ected at wavenumbers less than 0.03 h Mpc(-1), but the power spectrum is consistent with a change in slope from the k(-1.5) behaviour observ ed on smaller scales to a Zeldovich spectrum on large scales. In the w avenumber range considered, we find somewhat less power than in the op tically selected APM survey.