Galaxy Correlation Function Constraints on Large-Scale Structure

Abstract

We consider whether photometric errors may have induced the apparent large-scale, ≥10h ^-1 Mpc (where h is the Hubble constant in units of 100 km s^-1 Mpc^-1), power in the angular correlation function ω(θ) estimated from the APM galaxy catalogue. Using the galaxy CCD sequences on 39 of the plates in this catalogue we have made an independent estimate of the random and systematic errors in the APM magnitude scale. In particular we have found that the rms error in the plate zero-points is 0.^m084, a factor of ∼2 larger than the estimate found by Maddox et al. (1990b). Further, the distribution of the zero-point residuals over the APM survey area suggests that much of this extra error could arise from large-scale magnitude correlations. Thus, taking these observations into account in the estimate of ω(θ), it is shown that the excess power in the galaxy correlation function may be due to photometric calibration errors and that the standard CDM galaxy formation model may not be in contradiction with the observations.