THE LUMINOSITY FUNCTION OF Z-GREATER-THAN-4 QUASARS FROM THE 2ND PALOMAR SKY SURVEY

This paper is the second in a series of papers describing the search f or z > 4 quasars using the digitized Second Palomar Sky Survey. This i s a photographic multicolor search in three bands, JFN, calibrated to Gunn-Thuan gri, over the range 16.5(m) < r < 19.6(m). In the first pap er, the search techniques were described and the discovery of our firs t six quasars (five previously unknown) was reported. Here we report t he discovery of four additional new quasars, and present coordinates, finding charts, and spectra for these objects. In addition, we describ e our adopted candidate selection procedures developed in light of our initial discoveries. The selection criteria have been applied objecti vely to our data sets, allowing us to estimate our survey completeness through Monte Carlo simulations, and calculate quasar space densities at high redshift. So far, we have covered 27 plate fields, for an eff ective area of 681 deg(2). Follow-up spectroscopy is complete for larg e portions of the color-color space. At our median redshift of z = 4.3 5, we find that quasar space densities are down by a factor of 7 from z = 2.0, and we see no evidence for luminosity dependent density evolu tion from z = 2 to z = 4. We discuss how these findings compare to oth er surveys for quasars at high redshift. (C) 1995 American Astronomica l Society.