Related papers: Are there broad absorption-line blazars?
Using the radio observations by FIRST and NVSS, we build a sample of 151 radio variable quasars selected from the Sloan Digital Sky Survey Data Release 3 (SDSS DR3). Six (probably another two) among them are classified as broad absorption…
We present combined $\approx 14-37~\rm ks$ Chandra observations of seven $z = 1.6-2.7$ broad absorption line (BAL) quasars selected from the Large Bright Quasar Survey (LBQS). These seven objects are high-ionization BAL (HiBAL) quasars, and…
We present the variability study of broad absorption lines (BALs) in a uniformly radio-selected sample of 28 BAL quasars using the archival data from the FIRST Bright Quasar Survey (FBQS) and the Sloan Digital Sky Survey (SDSS), as well as…
We present the results of an optical photometric monitoring program of 10 extremely radio loud broad absorption line quasars (RL-BALQSOs) with radio-loudness parameter, R, greater than 100 and magnitude g_i < 19. Over an observing run of…
We present statistical and monitoring results of narrow absorption lines that are physically related to quasars (i.e., intrinsic NALs). We use Keck/HIRES spectra of 37 optically bright quasars at z=2-4, and identify 150 NAL systems that…
Based on a recently started programme, we report the first search for intranight optical variability among radio-quiet weak-line-quasars (RQWLQs). Eight members of this class were observed on 13 nights in the R-band, such that each source…
We compile a large sample of broad absorption lines (BAL) quasars with X-ray observations from the \xmm archive data and Sloan Digital Sky Survey Data Release 5. The sample consists of 41 BAL QSOs. Among 26 BAL quasars detected in X-ray,…
Using a sample of $\simeq$144,000 quasars from the Sloan Digital Sky Survey data release 14 we investigate the outflow properties, evident both in absorption and emission, of high-ionization Broad Absorption Line (BAL) and non-BAL quasars…
We present 21 examples of C IV Broad Absorption Line (BAL) trough disappearance in 19 quasars selected from systematic multi-epoch observations of 582 bright BAL quasars (1.9 < z < 4.5) by the Sloan Digital Sky Survey-I/II (SDSS-I/II) and…
Broad absorption lines (BALs) found in a significant fraction of quasar spectra identify high-velocity outflows that might be present in all quasars and could be a major factor in feedback to galaxy evolution. Understanding the nature of…
We present 13 Broad Absorption Line (BAL) quasars, including 12 new objects, which were identified in the Sloan Digital Sky Survey (SDSS) and matched within 2'' to sources in the FIRST radio survey catalog. The surface density of this…
Broad absorption lines seen in some quasars prove the existence of ionized plasma outflows from the accretion disk. Outflows together with powerful jets are important feedback processes. Understanding physics behind BAL outflows might be a…
We present a new set of 84 Broad absorption line (BAL) quasars ( 1.7 $<$ \zem $<$ 4.4) exhibiting an appearance of \civ BAL troughs over 0.3$-$4.8 rest-frame years by comparing the Sloan Digital Sky Survey Data Release (SDSSDR)-7,…
We report the discovery of five broad-absorption-line (BAL) QSOs in a complete sample of 111 ultraviolet excess (UVX) QSO candidates also detected in the NRAO VLA Sky Survey. All five BAL QSOs, which include two high-ionization BAL QSOs and…
Broad absorption line (BAL) quasars have been studied for over thirty years. Yet it is still unclear why and when we observe broad absorption lines in quasars. Is this phenomenon caused by geometry or is it connected with the evolution…
In a spectroscopic follow-up to the VLA FIRST survey, the FIRST Bright Quasar Survey (FBQS) has found 29 radio-selected broad absorption line (BAL) quasars. This sample provides the first opportunity to study the properties of…
It is widely accepted that the broad absorption line region (BALR) exists in most (if not all) quasars with a small covering factor. Recent works showed that the BALR is optically thick to soft and even medium energy X-rays, with a typical…
Broad absorption line (BAL) quasars serve as critical probes for understanding active galactic nucleus (AGN) outflows, black hole accretion, and cosmic evolution. To address the limitations of manual classification in large-scale…
We have discovered two low-ionization broad absorption line quasars in programs to obtain optical spectra for radio-selected quasar candidates from the VLA FIRST Survey (Becker, White, & Helfand 1995). Both belong to the extremely rare…
We are in the process of obtaining a complete sample of exploratory X-ray observations of broad absorption line (BAL) QSOs from the Large Bright Quasar Survey (LBQS). This survey is composed of short (5-7 ks) Chandra ACIS-S3 observations…