Kavli Affiliate: Claudio Ricci
| First 5 Authors: , , , ,
| Summary:
Broad absorption line (BAL) quasars are often considered X-ray weak relative
to their optical/UV luminosity, whether intrinsically (i.e., the coronal
emission is fainter) or due to large column densities of absorbing material.
The SDSS-V is providing optical spectroscopy for samples of quasar candidates
identified by eROSITA as well as Chandra, XMM or Swift, making the resulting
datasets ideal for characterising the BAL quasar population within an X-ray
selected sample. We use the Balnicity Index (BI) to identify the BAL quasars
based on absorption of the CIV $lambda,1549$ emission line in the optical
spectra, finding 143 BAL quasars in our sample of 2317 X-ray selected quasars
within $1.5le z le3.5$. This observed BAL fraction of $approx$ 6 per cent is
comparable to that found in optically selected samples. We also identify
absorption systems via the Absorption Index (AI) which includes mini-BALs and
NALs, finding 954 quasars with AI $>0$. We consider the CIV emission space
(equivalent width vs. blueshift) to study the BAL outflows within the context
of the radiatively driven accretion disc-wind model. X-ray selection excludes
the highest outflow velocities in emission but includes the full range of
absorption velocities which we suggest is consistent with the BAL gas being
located further from the X-ray corona than the emitting gas. We observe both
X-ray weak and X-ray strong BALs (via the optical-to-X-ray spectral slope,
$alpha_textox$) and detect little evidence for differing column densities
between the BAL and non-BAL quasars, suggesting the BALs and non-BALs have the
same shielding gas and intrinsic X-ray emission.
| Search Query: ArXiv Query: search_query=au:”Claudio Ricci”&id_list=&start=0&max_results=3