Properties of active galaxies at the extreme of Eigenvector 1
Center for Theoretical Physics, Polish Academy of Sciences,
Al. Lotników 32/46,
2 Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warsaw, Poland
3 Copernicus Astronomical Center, Bartycka 18, 00-716 Warsaw, Poland
4 School of Physics and Technology, Wuhan University, Wuhan 430072, PR China
5 Key Laboratory for Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, 19B Yuquan Road, Beijing 100049, PR China
Accepted: 3 January 2018
Context. Eigenvector 1 (EV1) is the formal parameter which allows the introduction of some order in the properties of the unobscured type 1 active galaxies.
Aims. We aim to understand the nature of this parameter by analyzing the most extreme examples of quasars with the highest possible values of the corresponding eigenvalues RFe.
Methods. We selected the appropriate sources from the Sloan Digital Sky Survey (SDSS) and performed detailed modeling, including various templates for the Fe II pseudo-continuum and the starlight contribution to the spectrum.
Results. Out of 27 sources with RFe larger than 1.3 and with the measurement errors smaller than 20% selected from the SDSS quasar catalog, only six sources were confirmed to have a high value of RFe, defined as being above 1.3. All other sources have an RFe of approximately 1. Three of the high RFe objects have a very narrow Hβ line, below 2100 km s−1 but three sources have broad lines, above 4500 km s−1, that do not seem to form a uniform group, differing considerably in black hole mass and Eddington ratio; they simply have a very similar EW([OIII]5007) line. Therefore, the interpretation of the EV1 remains an open issue.
Key words: quasars: emission lines / accretion, accretion disks
© ESO 2018