Blue outliers among intermediate redshift quasars

[OIII]λ5007$\mathrm{[OIII]}\lambda 5007$ “blue outliers”—that are suggestive of outflows in the narrow line region of quasars—appear to be much more common at intermediate z$z$ (high luminosity) than at low z$z$. About 40%$40~\%$ of quasars in a Hamburg ESO intermediate z$z$ sample of 52 sources qualify as “blue outliers” (i.e., quasars with [OIII]λλ4959,5007$\mbox{[OIII]}\lambda\lambda 4959,5007$ lines showing large systematic blueshifts with respect to rest frame). We discuss major findings on what has become an intriguing field in active galactic nuclei research and stress the relevance of “blue outliers” to feedback and host galaxy evolution. © 2015, Springer Science+Business Media Dordrecht.