Variability of Low-ionization Broad Absorption Line Quasars Based on Multi-epoch Spectra from The Sloan Digital Sky Survey

Abstract

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 Sky Survey, which has delivered the largest such BAL-variability sample ever studied. \mgii-BAL identifications and related measurements are compiled and presented in a catalog. We find a remarkable time-dependent asymmetry in EW variation from the sample, such that weakening troughs outnumber strengthening troughs, the first report of such a phenomenon in BAL variability. Our investigations of the sample further reveal that (i) the frequency of BAL variability is significantly lower (typically by a factor of 2) than that from high-ionization BALQSO samples; (ii) \mgii\ BAL absorbers tend to have relatively high optical depths and small covering factors along our line of sight; (iii) there is no significant EW-variability correlation between \mgii\ troughs at different velocities in the same quasar; and (iv) the EW-variability correlation between \mgii\ and \aliii\ BALs is significantly stronger than that between \mgii\ and \civ\ BALs at the same velocities. These observational results can be explained by a combined transverse-motion/ionization-change scenario, where transverse motions likely dominate the strengthening BALs while ionization changes and/or other mechanisms dominate the weakening BALs.

24 pages, accepted for publication in ApJS

References in corpus (60)

• The Sloan Digital Sky Survey: Technical Summary
• Energy input from quasars regulates the growth and activity of black holes and their host galaxies
• Observational Evidence of AGN Feedback
• The 2.5 m Telescope of the Sloan Digital Sky Survey
• SDSS-III: Massive Spectroscopic Surveys of the Distant Universe, the Milky Way Galaxy, and Extra-Solar Planetary Systems
• Composite Quasar Spectra From the Sloan Digital Sky Survey
• A Catalog of Quasar Properties from SDSS DR7
• The Multi-Object, Fiber-Fed Spectrographs for SDSS and the Baryon Oscillation Spectroscopic Survey
• The Sloan Digital Sky Survey Quasar Catalog V. Seventh Data Release
• The Sloan Digital Sky Survey Quasar Catalog: twelfth data release
• A Catalog of Broad Absorption Line Quasars from the Sloan Digital Sky Survey Third Data Release
• A Catalog of Broad Absorption Line Quasars in Sloan Digital Sky Survey Data Release 5
• Unusual Broad Absorption Line Quasars from the Sloan Digital Sky Survey
• Improved redshifts for SDSS quasar spectra
• Properties of Radio-Selected Broad Absorption-Line Quasars from the FIRST Survey
• Fe II Emission in 14 Low-Redshift Quasars: I - Observations
• The Black Hole Mass - Galaxy Bulge Relationship for QSOs in the SDSS DR3
• Feedback from Mass Outflows in Nearby Active Galactic Nuclei I. UV and X-ray Absorbers
• The Sloan Digital Sky Survey Reverberation Mapping Project: Velocity Shifts of Quasar Emission Lines
• Broad Absorption Line Variability on Multi-Year Timescales in a Large Quasar Sample
• Quasar Broad Absorption Line Variability on Multi-Year Time Scales
• Broad Absorption Line Disappearance on Multi-Year Timescales in a Large Quasar Sample
• Major contributor to AGN feedback: VLT X-shooter observations of SIV BAL QSO outflows
• A High-Velocity Narrow Absorption Line Outflow in the Quasar J212329.46-005052.9
• Variability in Quasar Broad Absorption Line Outflows I. Trends in the Short-Term versus Long-Term Data
• HST Observations of the Broad Absorption Line Quasar PG 0946+301
• Broad Absorption Line Variability in Repeat Quasar Observations from the Sloan Digital Sky Survey
• Variability in quasar broad absorption line outflows II. Multi-epoch monitoring of SiIV and CIV BAL variability
• Implications of Dramatic Broad Absorption Line Variability in the Quasar FBQS J1408+3054
• Extreme-Velocity Quasar Outflows and the Role of X-ray Shielding
• Evidence that 50% of BALQSO Outflows Are Situated at Least 100 pc from the Central Source
• The Sloan Digital Sky Survey Reverberation Mapping Project: Rapid CIV Broad Absorption Line Variability
• Low-z MgII Broad Absorption-Line Quasars from the Sloan Digital Sky Survey
• The Evolution of Quasar CIV and SiIV Broad Absorption Lines Over Multi-Year Time Scales
• Evidence for Photoionization Driven Broad Absorption Line Variability
• LBQS 0103-2753: A 0.3 Arcsec Binary Quasar
• The Sloan Digital Sky Survey Reverberation Mapping Project: Ensemble Spectroscopic Variability of Quasar Broad Emission Lines
• On the structure and energetics of quasar broad absorption-line outflows
• Variation of ionizing continuum: the main driver of Broad Absorption Line Variability
• The Dependence of C IV Broad Absorption Line Properties on Accompanying Si IV and Al III Absorption: Relating Quasar-Wind Ionization Levels, Kinematics, and Column Densities
• Broad absorption line disappearance and emergence using multiple-epoch spectroscopy from the Sloan Digital Sky Survey
• Radiation pressure confinement - IV. Application to broad absorption line outflows
• CIV Broad Absorption Line Acceleration in Sloan Digital Sky Survey Quasars
• Broad Absorption Line Quasars with Redshifted Troughs: High-Velocity Infall or Rotationally Dominated Outflows?
• Variability in Low Ionization Broad Absorption Line Outflows
• Dynamically evolving Mg II broad absorption line flow in SDSS J133356.02+001229.1
• Probing the time variability of five Fe low broad absorption line quasars
• Near-IR spectroscopy of luminous LoBAL quasars at 1<z<2.5
• Emergence and Variability of Broad Absorption Line Quasar Outflows
• Emergence of a Quasar Outflow
• A multi-epoch spectroscopic study of the BAL quasar APM 08279+5255: I. C IV absorption variability
• Broad Absorption Line Variability in Radio-Loud Quasars
• Constraining FeLoBAL outflows from absorption line variability
• Strong Variability of Overlapping Iron Broad Absorption Lines in Five Radio-selected Quasars
• C IV BAL disappearance in a large SDSS QSO sample
• Transient C IV Broad Absorption Lines in radio detected QSOs
• Broad absorption line disappearance/emergence in multiple ions in a weak emission-line quasar
• Extreme Variability in a Broad Absorption Line Quasar
• Vanishing Absorption and Blueshifted Emission in FeLoBAL Quasars
• The physical constraints on a new LoBAL QSO at z=4.82

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• Spectroscopy of broad absorption line quasars at $3\lesssim z\lesssim 5$ -- I: evidence for quasar winds shaping broad/narrow emission line regions
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• Multi-epoch spectroscopy of Mg II broad absorption line transitions
• Physical characterization of the FeLoBAL outflow in SDSS J0932+0840: Analysis of VLT/UVES observations
• Radio Scrutiny of the X-ray-Weak Tail of Low-Mass Active Galactic Nuclei: A Novel Signature of High-Eddington Accretion?
• Spectroscopic Quasar Anomaly Detection (SQuAD) I: Rest-Frame UV Spectra from SDSS DR16
• Transient LoBALs at high velocities: A Case of Extreme Broad Absorption Line Variability in J115636.82+085628.9
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