Survey for galaxies associated with z∼3 damped Lyα systems.: II.: Galaxy-absorber correlation functions

We use 211 galaxy spectra from our survey for Lyman break galaxies (LBGs) associated with 11 damped Ly alpha systems (DLAs) to measure the three-dimensional LBG autocorrelation and DLA-LBG cross-correlation functions with the primary goal of inferring the mass of DLAs at z similar to 3. From every measurement and test in this work, we find evidence for an overdensity of LBGs near DLAs that is very similar to that of LBGs near other LBGs. Conventional binning of the data while varying both r(0) and gamma parameters of the fiducial model of the correlation function xi(r) = (r/r(0))(-gamma) resulted in the best-fit values and 1 sigma uncertainties of r(0) = 2.65 +/- 0.48; gamma = 1.55 +/- 0.40 for the LBG autocorrelation, and r(0) = 3.32 +/- 1.25; gamma = 1.74 +/- 0.36 for the DLA-LBG cross-correlation function. To circumvent shortcomings found in binning small data sets, we perform a maximum likelihood analysis based on Poisson statistics. The best-fit values and 1 sigma confidence levels were found to be r(0) = 2.91(-1.0)(+1.0), gamma = 1.21(-0.3)(+0.6) for the LBG autocorrelation, and r(0) = 2.81(-2.0)(+1.4), gamma = 2.11(-1.4)(+1.3) for the DLA-LBG cross-correlation function. We report a redshift spike of five LBGs with Delta z = 0.015 of the z = 2.936 DLA in the PSS 0808+5215 field; the DLA-LBG clustering signal survives when omitting this field from the analysis. Using the correlation function measurements and uncertainties, we compute the z similar to 3 LBG galaxy bias b(LBG) to be 1.5 < b(LBG) < 3, corresponding to an average halo mass of 10(9.7) < < M-LBG > < 10(11.6) M-circle dot, and the z similar to 3 DLA galaxy bias b(DLA) to be 1.3 < b(DLA) < 4, corresponding to an average halo mass of 10(9) < < M-LBG > < 10(12) M-circle dot. Finally, two of the six QSOs discovered were found to lie within Delta z = 0.0125 of two of the survey DLAs. We estimate that the probability of this occurring by chance is 1 in 940, indicating a possible relationship between the distribution of QSOs and DLAs at z similar to 3.