Related papers: Extreme Variability in a Broad Absorption Line Qua…
The intergalactic medium was not completely reionized until approximately a billion years after the Big Bang, as revealed by observations of quasars with redshifts of less than 6.5. It has been difficult to probe to higher redshifts,…
Very few low-ionization broad absorption line (LoBAL) QSOs have been found at high redshifts to date. One high-redshift LoBAL QSO, J0122+1216, was recently discovered at the Lijiang 2.4-m Telescope with an initial redshift determination of…
We investigate C IV broad absorption line (BAL) variability within a sample of 46 radio-loud quasars (RLQs), selected from SDSS/FIRST data to include both core-dominated (39) and lobe-dominated (7) objects. The sample consists primarily of…
Multi-frequency 1.7, 5 and 8.4-GHz VLBA observations of a radio-loud broad absorption line (BAL) quasar 1045+352 are presented. It is a young compact steep spectrum (CSS) object and its asymmetric, two-sided morphology on a scale of several…
Spectroscopic observations of the quasar J0950$+$5128 spanning 22 years reveal monotonic radial velocity variations in its broad H$\beta$ emission line. Moreover, the line profile becomes broader over time, necessitating careful…
We present a time-variability analysis of 29 broad absorption line quasars (BALQSOs) observed in two epochs by the Sloan Digital Sky Survey (SDSS). These spectra are selected from a larger sample of BALQSOs with multiple observations by…
We present the optical-near infrared spectral energy distributions (SED) and near infrared variability properties of 30 low-redshift iron low-ionization Broad Absorption Line quasars (FeLoBALQs) and matched samples of LoBALQs and unabsorbed…
We report the discovery of a z=2.65 low-ionization iron broad absorption line quasar, FIRST J100424.9+122922, which is gravitationally-lensed by a galaxy at z~0.95. The object was discovered as part of a program to find very red quasars by…
We report the detection of the H_2O molecule in absorption at a redshift z = 0.68466 in front of the gravitationally lensed quasar B0218+357. We detect the fundamental transition of ortho-water at 556.93 GHz (redshifted to 330.59 GHz). The…
The brightest southern quasar above redshift $z=1$, HE 0515$-$4414, with its strong intervening metal absorption-line system at $z_{abs}=1.1508$, provides a unique opportunity to precisely measure or limit relative variations in the…
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…
The variability of broad absorption lines is investigated for a sample of 188 broad-absorption-line (BAL) quasars (QSOs) ($z > 1.7$) with at least two-epoch observations from the Sloan Digital Sky Survey Data Release 7 (SDSS DR7), covering…
Among the unusual broad absorption line quasars being found by the Sloan Digital Sky Survey (SDSS) are objects with much stronger absorption in Fe III than Fe II. These unusual line ratios require a high density in the outflow (n_H >= 3 x…
Time variability of astronomical sources provides crude information on their typical size and on the implied physical mechanisms. PKS1830-211 is a remarkable radio-bright lensed quasar with a foreground molecular absorber at z=0.89.…
We present absorption variability results for 134 bona fide \mgii\ broad absorption line (BAL) quasars at 0.46~$\lesssim z \lesssim$~2.3 covering days to $\sim$ 10 yr in the rest frame. We use multiple-epoch spectra from the Sloan Digital…
We present six new and two previously published high-resolution spectra of the quasar HS 1603+3820 (z_em = 2.542) taken over an interval of 4.2 years (1.2 years in the quasar rest frame). The observations were made with the High-Dispersion…
We report X-ray observations of the most distant known gravitationally lensed quasar, J0439+1634 at $z=6.52$, which is also a broad absorption line (BAL) quasar, using the XMM-Newton Observatory. With a 130 ks exposure, the quasar is…
We examine the variability of the high-ionization Lyman alpha lambda 1216 broad emission line (BEL) in a sample of 61 high-luminosity, high-redshift quasars observed at two epochs by the Sloan Digital Sky Survey. These bright objects lie in…
We report the discovery of unusual broad absorption lines (BALs) in the bright quasar SDSS J075133.35+134548.3 at z~1, and present a detailed study of BAL and emission lines using the archived and newly obtained optical and NIR…
We present absorption line analysis of the outflow in the quasar IRAS F04250-5718. Far-ultraviolet data from the Cosmic Origins Spectrograph onboard the Hubble Space Telescope reveal intrinsic narrow absorption lines from high ionization…