The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: the low redshift sample

TL;DR

This study analyzes the small-scale clustering of nearly 79,000 massive galaxies at low redshift from SDSS-III BOSS, using correlation functions and Halo Occupation Distribution modeling to understand their halo environments.

Contribution

It provides detailed clustering measurements and halo occupation insights for low-redshift massive galaxies, expanding understanding of galaxy-halo connections in this regime.

Findings

Galaxies reside in massive halos (~5.2x10^13 h^-1 M_sun)

Large scale bias is approximately 2.0

Satellite fraction is about 12%

Abstract

We report on the small scale (0.5<r<40h^-1 Mpc) clustering of 78895 massive (M*~10^11.3M_sun) galaxies at 0.2<z<0.4 from the first two years of data from the Baryon Oscillation Spectroscopic Survey (BOSS), to be released as part of SDSS Data Release 9 (DR9). We describe the sample selection, basic properties of the galaxies, and caveats for working with the data. We calculate the real- and redshift-space two-point correlation functions of these galaxies, fit these measurements using Halo Occupation Distribution (HOD) modeling within dark matter cosmological simulations, and estimate the errors using mock catalogs. These galaxies lie in massive halos, with a mean halo mass of 5.2x10^13 h^-1 M_sun, a large scale bias of ~2.0, and a satellite fraction of 12+/-2%. Thus, these galaxies occupy halos with average masses in between those of the higher redshift BOSS CMASS sample and the original SDSS I/II LRG sample.