Do broad absorption line quasars live in different environments from ordinary quasars?

Abstract

We select a sample of $\sim 4200$ traditionally defined broad absorption line quasars (BALQs) from the Fifth Data Release quasar catalog of the Sloan Digital Sky Survey. For a statistically homogeneous quasar sample with $1.7\le z\le 4.2$, the BAL quasar fraction is $\sim 14%$ and is almost constant with redshift. We measure the auto-correlation of non-BAL quasars (nonBALQs) and the cross-correlation of BALQs with nonBALQs using this statistically homogeneous sample, both in redshift space and using the projected correlation function. We find no significant difference between the clustering strengths of BALQs and nonBALQs. Assuming a power-law model for the real space correlation function $\xi(r)=(r/r_0)^{-1.8}$, the correlation length for nonBALQs is $r_0=7.6\pm 0.8 h^{-1}{\rm Mpc}$; for BALQs, the cross-correlation length is $r_0=7.4\pm 1.1 h^{-1}{\rm Mpc}$. Our clustering results suggest that BALQs live in similar large-scale environments as do nonBALQs.