First investigation of the clustering environment of damped Ly alpha absorbers at z similar or equal to 4

We report the first observations of the clustering environment of damped Ly man alpha absorption systems at z similar or equal to 4. Color selection an d photometric redshifts were used to select 44 candidate Lyman-break galaxi es brighter than I-AB = 25.5 from deep BRI images of the 35 arcmin(2) field containing the quasar BR 0951-04. Multislit spectroscopy of 35 candidate g alaxies was performed and eight of these candidates have been confirmed as z > 3.5 Lyman-break galaxies. With only BRI photometry, the photometric red shifts are quite accurate for the spectroscopically confirmed galaxies but have a high rate of misclassification due to color degeneracies between Lym an-break galaxies and low-redshift ellipticals. Both of the z > 3.5 galaxie s found within 15 " of the quasar line-of-sight appear to be causing absorp tion systems in the quasar spectrum. We use a battery of statistical tests to look for clustering in the redshift histogram of the z > 3.5 galaxies bu t do not find measurable clustering of these Lyman-break galaxies with the damped Ly alpha absorbers. With a larger sample of galaxies, our method sho uld determine the crosscorrelation between these objects, which probes the bias and hence the mass of the damped Ly alpha absorbers. absorbers.