The Small-Scale Clustering of Luminous Red Galaxies via Cross-Correlation Techniques


Eisenstein DJ, Blanton M, Zehavi I, Bahcall N, Brinkmann J, Loveday J, Meiksin A, Schneider D. The Small-Scale Clustering of Luminous Red Galaxies via Cross-Correlation Techniques. The Astrophysical Journal. 2005;619 :178-192.

Date Published:

January 1, 2005


We present the small-scale (0.2-7 h-1 Mpc) cross-correlationsbetween 32,000 luminous early-type galaxies and a reference sample of 16million normal galaxies from the Sloan Digital Sky Survey (SDSS). Ourmethod allows us to construct the spherically averaged, real-spacecross-correlation function between the spectroscopic luminous red galaxy(LRG) sample and galaxies from the SDSS imaging. We report thecross-correlation as a function of scale, luminosity, and redshift. Wefind very strong luminosity dependences in the clustering amplitudes, upto a factor of 4 over a factor of 4 in luminosity, and we measure thisdependence with a high signal-to-noise ratio. The luminosity dependenceof bias is found to depend on scale, with more variation on smallerscales. The clustering as a function of scale is not a power law butinstead has a dip at 1 h-1 Mpc and an excess on small scales.The fraction of red galaxies within the L* sample surroundingLRGs is a strong function of scale, as expected. However, the fractionof red galaxies evolves in redshift similarly on small and large scales,suggesting that cluster and field populations are changing in the samemanner. The results highlight the advantage on small scales of usingcross-correlation methods as a means of avoiding shot noise in samplesof rare galaxies.