The environment of active galaxies in the SDSS-DR4

  title={The environment of active galaxies in the SDSS-DR4},
  author={Gennaro Sorrentino and Mario Radovich and Agatino Rifatto},
  journal={Astronomy and Astrophysics},
Aims. We study the environment of active galaxies and compare it with that of star-forming and normal galaxies. Methods. From the Fourth Data Release (DR4) of the Sloan Digital Sky Survey (SDSS) we extracted the galaxies in the redshift range 0.05≤ z≤ 0.095 and with M(r)≤ −20.0 (that is, M ∗ + 1.45). Emission-line ratios and/or widths were used to separate active galactic nuclei (AGNs) from star-forming galaxies (SFGs); AGNs were classified as Seyfert-1 (Sy1) and Seyfert-2 (Sy2) galaxies… 

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