Published in Memorie della Societa Astronomica Italiana, v.76, p.21 (2005).
astro-ph/0411632

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Abstract. This article discusses the our changing knowledge of the evolution of AGN from an optical perspective. It focusses on optically-unobscured (type-1) AGN as it is much trickier to investigate the evolution type-2 objects from an optical point of view. It discusses major optical survey work that improved our knowledge of QSO evolution during the last five years. It touches on the shape of the QSO luminosity function, on the peak of QSO activity, the quest for reddened QSOs and spectral evolution. Finally, it summarizes recent advances in the research of host galaxies, which probably hold the key for the triggering mechanisms of the activity, and reiterates the difficulty of understanding the physical evolution of AGN and its place in the context of galaxy evolution.

Key words: Surveys -- Galaxies: active -- Galaxies: evolution -- quasars: general -- Cosmology: observations

Table of Contents

• INTRODUCTION
• QSO EVOLUTION - 5 YEARS AGO
• RECENT OPTICAL SURVEYS
• Shape of the luminosity function
• Peak of AGN activity
• Reddened QSOs
• Optically obscured QSOs
• Evolution of spectral properties
• HOST GALAXIES OF AGN
• AGN EVOLUTION IN THE CONTEXT OF GALAXY EVOLUTION
• SUMMARY
• REFERENCES