Astronomy and Astrophysics – Astrophysics – Cosmology and Extragalactic Astrophysics
Scientific paper
2010-12-11
Astronomy and Astrophysics
Astrophysics
Cosmology and Extragalactic Astrophysics
12 pages, 12 figures, 3 tables, accepted for publication in MNRAS
Scientific paper
We study the X-ray and optical properties of 16 Broad Absorption Line (BAL) quasars detected in about 3 degree square region common to the wide synoptic (W-1) component of the Canada-France-HawaiiTelescope Legacy Survey (CFHTLS) and the XMM Large Scale Structure survey (XMM-LSS). The BAL fraction is found to be 10% in full sample, 7% for the optical colour selected QSOs and as high as 33% if we consider QSOs selected from their IR colours. The X-ray detected non-BAL and BAL quasars have a mean observed X-ray-to-optical spectral slope of -1.47 +/- 0.13 and -1.66 +/- 0.17 respectively. We also find that the BAL QSOs have alpha_ox systematically smaller than what is expected from the relationship between optical luminosity and alpha_ox as derived from our sample. Based on this, we show, as already reported in the literature for quasars with high optical luminosities, our new sample of BAL QSOs have X-ray luminosity a factor of three smaller than what has been found for non-BAL QSOs with similar optical luminosities. Comparison of hardness ratio of the BAL and non-BAL QSOs suggests a possible soft X-ray weakness of BAL QSOs. Combining our sample, of relatively fainter QSOs, with others from the literature we show that larger balnicity index (BI) and maximum velocity (V_max) of the C IV absorption are correlated with steeper X-ray to optical spectral index. We argue that this is most likely a consequence of the existence of a lower envelope in the distribution of BI (or V_max) values versus optical luminosity. Our results thus show that the previously known X-ray weakness of BAL QSOs extends to lower optical luminosities as well.
Petitjean Patrick
Srianand Raghunathan
Stalin C. S.
No associations
LandOfFree
X-ray and optical properties of Broad Absorption Line Quasars in the Canada-France-Hawaii Telescope Legacy Survey 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 X-ray and optical properties of Broad Absorption Line Quasars in the Canada-France-Hawaii Telescope Legacy Survey, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and X-ray and optical properties of Broad Absorption Line Quasars in the Canada-France-Hawaii Telescope Legacy Survey will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-105468