Galaxy clustering in the Sloan Digital Sky Survey (SDSS): a first comparison with the APM Galaxy Survey

Abstract

We compare the large-scale galaxy clustering in the new Sloan Digital Sky Survey (SDSS) early data release (EDR) with the clustering in the APM Galaxy Survey. We cut out pixel maps (identical in size and shape) from the SDSS and APM data to allow a direct comparison of the clustering. Here we concentrate our analysis on an equatorial SDSS strip in the South Galactic Cap (EDR/SGC) of 166 deg 2 , 2°.5 wide and 65° long. Only galaxies with Petrosian magnitudes 16.8 < g' < 19.8 are included to match the surface density of the 17 < b J < 20 APM pixel maps (median depth of ∼400 h - 1 Mpc). Both the amplitude and the shape of the angular two-point function and variance turn out to be in very good agreement with the APM on scales smaller than 2° (or ≤ 15 h - 1 Mpc). The three-point function and skewness are also in excellent agreement within a 90 per cent confidence level. On the one hand these results illustrate that the EDR data and SDSS software pipelines work well and are suitable to carry out analysis of large-scale clustering. On the other hand they confirm that large-scale clustering analysis is becoming 'repeatable' and therefore that our conclusions for structure formation models seem to stand on solid scientific grounds.