Blue outliers among intermediate redshift quasars

TL;DR

This paper investigates the high occurrence of blue outliers, characterized by blueshifted [OIII] emission lines, in intermediate-redshift quasars, highlighting their significance for understanding active galactic nuclei feedback and galaxy evolution.

Contribution

It presents observational evidence that blue outliers are more common at intermediate redshifts and discusses their implications for AGN feedback and host galaxy evolution.

Findings

Approximately 40% of intermediate-z quasars are blue outliers.

Blue outliers are more prevalent at high luminosity and intermediate redshift.

Blue outliers are linked to outflows in the narrow line region of quasars.

Abstract

[Oiii]{\lambda}{\lambda}4959,5007 "blue outliers" -- that are suggestive of outflows in the narrow line region of quasars -- appear to be much more common at intermediate z (high luminosity) than at low z. About 40% of quasars in a Hamburg ESO intermediate-z sample of 52 sources qualify as blue outliers (i.e., quasars with [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.