3.2 Galaxy Power-Spectrum

The power-spectrum (PS) of galaxies in redshift space has been computed for a number of optical (e.g., Park et al. 1992, Park et al. 1994, da Costa et al. 1994b, Lin et al. 1996b) and infrared surveys (Fisher et al. 1993). The redshift-space PS estimates roughly follow a power-law P (k) kⁿ with a slope ranging from n ~ -2 on small scales ( 30 h^-1 Mpc) to n ~ -1.1 on intermediate scales (30 h^-1 < < 120 h^-1 Mpc). For nearby samples, such as the combined CfA2-SSRS2, one finds that the PS continues to rise on scales up to ~ 200 h^-1 Mpc. This result has been confirmed by similar analysis of other optical and infrared-selected samples, all showing essentially the same shape, while differences in the amplitude can be ascribed to the relative bias between optically and infrared-selected galaxies or between galaxies of different luminosities. These earlier results have been confirmed by the PS computed from the LCRS which shows good agreement with previous calculations on scales 100 h^-1 Mpc. On larger scales, the LCRS PS shows a change in slope and strongly suggests that it has detected the turnover. A good fit for the observed PS in redshift space, satisfying the constraints implied by COBE, can be obtained with a open or flat nonzero cosmological constant CDM model with a shape parameter = h = 0.2 with no bias. However, several other models are equally viable (da Costa et al. 1994b, Lin et al. 1996b).