The environment of weak emission-line quasars

Details The environment of weak emission-line quasars The environment of weak emission-line quasars

2011-11-16

arxiv.org/abs/1111.3909v2

Astronomy and Astrophysics

Astrophysics

Cosmology and Extragalactic Astrophysics

9 pages, 3 figures, 2 tables. Accepted for publication in MNRAS. Minor changes (corrected typos) to match published version

Scientific paper

10.1111/j.1365-2966.2011.20216.x

The nature of weak emission-line quasars (WLQs) is probed by comparing the Baldwin effect (BEff) in WLQs and normal quasars (QSOs). We selected 81 high-redshift (z>2.2) and 2 intermediate-redshift (z=1.66 and 1.89) WLQs. Their rest-frame equivalent widths (EWs) of the C IV emission-line and their Eddington ratio were obtained from the Sloan Digital Sky Survey Data Release 7 (SDSS DR7) Quasar Catalogue or from Diamond-Stanic et al. We compare the parameters of WLQs with these of 81 normal quasars from Bright Quasar Survey (BQS) and 155 radio-quiet and radio-intermediate quasars detected by SDSS and Chandra. The influence of the Eddington ratio, Lbol/Ledd, and the X-ray to optical luminosity ratio,alpha_ox, on the BEff is analysed. We find that WLQs follow a different relationship on the EW(CIV)-Lbol/Ledd plane than normal quasars. This relationship disagrees with the super-Eddington hypothesis. The weakness/absence of emission-lines in WLQs does not seem to be caused by their extremely soft ionizing continuum but by low covering factor (Omega) of their broad line region (BLR). Comparing emission-line intensities indicates that the ratios of high-ionization line and low-ionization line regions (i.e. Omega_(HIL)/Omega_(LIL)) are lower in WLQs than in normal QSOs. The covering factor of the regions producing C IV and Lyalpha emission-lines are similar in both WLQs and QSOs.

Affiliated with

Also associated with

No associations

Rating

The environment of weak emission-line quasars does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with The environment of weak emission-line quasars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The environment of weak emission-line quasars will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-69589