The low-redshift quasar-quasar correlation function from an extragalactic H alpha emission-line survey to z=0.4

We study the large-scale spatial distribution of low-redshift quasars and S eyfert 1 galaxies using a sample of 106 luminous emission-line objects ((M) over barB approximate to -23) selected by their H alpha emission lines in a far-red objective prism survey (0.2 < z < 0.37). Of the 106 objects, 25 w ere previously known active galactic nuclei (AGNs), and follow-up spectrosc opy for an additional 53 objects (including all object pairs with separatio n r < 20 h(-1) Mpc) confirmed 48 AGNs and 5 narrow emission line galaxies ( NELGs). The calculated amplitude of the spatial two-point correlation funct ion for the emission-line sample is A = 0.4<(xi )over bar>(r < 20 h(-1) Mpc ) x 20(1.8) = 142 +/- 53. Eliminating the confirmed NELGs from the sample, we obtain the AGN clustering amplitude A = 98 +/- 54. Using Monte Carlo sim ulations, we reject the hypothesis that the observed pair counts were drawn from a random distribution at the 99.97% and 98.6% confidence levels for t he entire sample and the AGN subset, respectively. We measure a decrease in the quasar clustering amplitude by a factor of 3.7 +/- 2.0 between z = 0.2 6 and z <approximate to> 1.5, and present the coordinates, redshifts, and f ollow-up spectroscopy for the 15 previously unknown AGNs and four luminous NELGs that contribute to the clustering signal.