The Two-Dimensional Power Spectrum of the Las Campanas Redshift Survey: Detection of Excess Power on 100 ITALh/ITALTSUP−1/TSUP Mpc Scales

We have measured the two-dimensional power spectrum of the Las Campanas Redshift Survey on scales between 30 and 200 h -1 Mpc ( q 0 = 0.5, H 0 = 100 h km s -1 Mpc -1 ). Such an analysis is more sensitive to structure on scales greater than 50 h -1 Mpc than a full three-dimensional analysis, given the geometry of the survey. We find a strong peak in the power spectrum at ~100 h -1 Mpc relative to the smooth continuum expected from the best-fit cold dark matter model (Prob ~ 2.5 × 10 -4 with Ω h = 0.3 assuming a Gaussian random field). This signal is detected in two independent directions on the sky and has been identified with numerous structures visible in the survey that appear as walls and voids. Therefore, we conclude that there exists a significant increase in power on this scale and that such structures are common features in the local universe, z ≤ 0.2.