Extended emission-line regions in low-redshift quasars ^*

Dependence on nuclear spectral properties

¹ Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany e-mail: bhusemann@aip.de
² Centro Astronómico Hispano Alemán de Calar Alto (CSIC-MPIA), 4004 Almería, Spain
³ Max-Planck-Institut für Astronomie, Königsstuhl 17, 69117 Heidelberg, Germany

Received: 28 May 2008
Accepted: 3 July 2008

Abstract

Aims. We searched for the presence of extended emission-line regions (EELRs) around low-redshift QSOs.

Methods. We observed a sample of 20 mainly radio-quiet low-redshift quasars ( by means of integral field spectroscopy. After decomposing the extended and nuclear emission components, we constructed []  narrow-band images of the EELR to measure the total flux. From the same data we obtained high (>50) nuclear spectra to measure properties such as []/Hβ flux ratios,  equivalent widths and Hβ line widths.

Results. A significant fraction of the quasars (8/20) show a luminous EELR, with detected linear sizes of several kpc. Whether or not a QSO has a luminous EELR is strongly related with nuclear properties, in the sense that an EELR was detected in objects with low  equivalent width and large Hβ . The EELRs were detected preferentially in QSOs with larger black hole masses. There is no discernible relation, however, between EELR detection and QSO luminosity and Eddington ratio.