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

To investigate the spatial distribution of low redshift quasars and luminous Seyfert 1, we have conducted a large area objective prism survey for extragalactic emission line sources. With the unique far red bandpass of the observations (6000 < lambda < 9200 A), we are able to identify AGN by their Halpha emission to z = 0.4 for the first time. In contrast to searching for blue point sources, this technique is independent of object color and morphology. We demonstrate a high completeness (from ≲ 100% at mB = 12 to about 80% at mB = 18, tapering off to zero at mB ≳ 20), and a high selection efficiency of ≳ 90% (at bright and faint magnitudes, unlike UV-excess selection). The quasar sample contains previously unknown luminous quasars in the local universe (including an MB = -26.5 +/- 0.5 quasar at z = 0.28) and red low z quasars with (B-V) > 1.; The objective prism data were taken during several nights in early 1999 with the QUEST 16 CCD driftscan camera on the 1m Venezuelan Schmidt telescope. The survey covers 700 deg2 in the equatorial region and contains 719 emission line objects (11% previously known) with magnitudes 9.7 ≤ mB ≤ 20.2. Follow-up spectroscopy for 149 emission line objects confirms 33 low redshift quasars and Seyfert 1 (z ≤ 0.37), 21 Liners and Seyfert 2 (z ≤ 0.49), 4 quasars (1.5 ≤ z ≤ 2.8) and 91 star forming galaxies.; We develop a classification scheme to identify low z quasars in the emission line catalog, and produce a sample of 136 AGN at 0.2 < z < 0.37, with redshift uncertainties sigma z = 0.003. With Monte Carlo simulations we reject the hypothesis that these pairs were drawn from a random sample at the 97.5% and 99.97% confidence levels respectively. This appears to be the strongest detection of clustering in Seyfert 1 and low z quasars ( z ≲ 0.3), and the first from an optically-selected sample.; We apply simple evolution models to compare the measured clustering amplitude, A=0.4˙x&d1; r<15h-1Mpc ˙151.8=125+/-51 , to that of galaxy systems in the local universe and quasars at z > 1. Evidence is provided for the group environment model and comoving: or stable evolution. By comparison to imaging studies of the environments of quasars at low redshift, we infer that quasars and luminous Seyfert 1 at z ≲ 0.3 are useful tracers of the large scale structure seen in galaxy redshift surveys, with a bias comparable to groups of galaxies. We find a decrease in the quasar clustering amplitude by a factor of 3.8 between z = 0.26 and z ≈ 1.5 (consistent with stable evolution at the 1sigma level but inconsistent with comoving and collapsing evolution at the ≳ 2sigma level). (Abstract shortened by UMI.)...