The Large-Scale 3-point correlation function of SDSS Luminous Red Galaxies

We present new measurements of the redshift-space three-point correlation function (3PCF) of Luminous Red Galaxies (LRGs) from the Sloan Digital Sky Survey (SDSS). Using the largest dataset to date, the Data Release 7 (DR7) LRGs, and an improved binning scheme compared to previous measurements, we measure the LRG 3PCF on large scales up to ~90 Mpc/h, from the mildly non-linear to quasi-linear regimes. Comparing the LRG correlations to the dark matter two- and three-point correlation functions, obtained from N-body simulations we infer linear and non-linear bias parameters. As expected, LRGs are highly biased tracers of large scale structure, with a linear bias b1 ~ 2; the LRGs also have a large positive non-linear bias parameter, in agreement with predictions of galaxy population models. The use of the 3PCF to estimate biasing helps to also make estimates of the cosmological parameter {\sigma_8}, as well as to infer best-fit parameters of the Halo Occupation Distribution parameters for LRGs. We also use a large suite of public mock catalogs to characterize the error covariance matrix for the 3PCF and compare the variance among simulation results with jackknife error estimates.