QSO/AGN environments at different redshifts

Abstract With the availability of large data sets like the Sloan Digital Sky Survey (SDSS) is it now possible to study a huge amount of galaxy spectra in a statistical manner. The spectroscopical data set of the seventh SDSS data release covers 9380 deg 2 (≈23% of the whole sky). We selected nearly 1 00 000 objects from this SDSS data release 7 that were spectroscopically classified as quasars to investigate their environment. We developed a dedicated software-pipeline to process this enormous amount of data. We classified all galaxies within the Quasar/AGN-neighbourhood of 1 Mpc according to Kauffmann, 2003 , Kewley et al., 2006 by mean of a diagnostic BPT diagram. For doing this we had to measure the narrow Balmer-line components manually. Furthermore, we studied the distribution of these objects in the QSO/AGN environment as well as their spectroscopical properties and the absolute magnitudes .