Spectral Variability of a Sample of Extreme Variability Quasars and Implications for the MgII Broad-line Region

Abstract

We present new Gemini/GMOS optical spectroscopy of 16 extreme variability quasars (EVQs) that dimmed by more than 1.5 mag in the $g$ band between the Sloan Digital Sky Survey (SDSS) and the Dark Energy Survey (DES) epochs (separated by a few years in the quasar rest frame). The quasar sample covers a redshift range of $0.5<z<2.1$. Nearly half of these EVQs brightened significantly (by more than 0.5 mag in the $g$ band) in a few years after reaching their previous faintest state, and some EVQs showed rapid (non-blazar) variations of greater than 1-2 mag on timescales of only months. Leveraging on the large dynamic range in continuum variability between the earlier SDSS and the new GMOS spectra, we explore the associated variations in the broad Mg II,$\lambda 2798$ line, whose variability properties have not been well studied before. The broad Mg II flux varies in the same direction as the continuum flux, albeit with a smaller amplitude, which indicates at least some portion of Mg II is reverberating to continuum changes. However, the width (FWHM) of Mg II does not vary accordingly as continuum changes for most objects in the sample, in contrast to the case of the broad Balmer lines. Using the width of broad Mg II to estimate the black hole mass therefore introduces a luminosity-dependent bias.

arXiv commentSubmitted to MNRAS

References in corpus (66)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• The Seventh Data Release of the Sloan Digital Sky Survey
• Unified Schemes for Radio-Loud Active Galactic Nuclei
• The 2.5 m Telescope of the Sloan Digital Sky Survey
• A Catalog of Quasar Properties from SDSS DR7
• The Dark Energy Camera
• Central Masses and Broad-Line Region Sizes of Active Galactic Nuclei: I. Comparing the Photoionization and Reverberation Techniques
• The cosmological evolution of quasar black-hole masses
• An Empirical Ultraviolet Template for Iron Emission in Quasars as Derived from I Zw 1
• Biases in Virial Black Hole Masses: An SDSS Perspective
• The Dark Energy Survey Data Release 1
• The Ensemble Photometric Variability of ~25000 Quasars in the Sloan Digital Sky Survey
• The Sloan Digital Sky Survey-II Supernova Survey: Technical Summary
• The Sloan Digital Sky Survey Quasar Catalog: Fourteenth Data Release
• Measuring the black hole masses of high redshift quasars
• The Discovery of the First "Changing Look" Quasar: New Insights into the Physics & Phenomenology of AGN
• SDSS Standard Star Catalog for Stripe 82: the Dawn of Industrial 1% Optical Photometry
• A Systematic Search for Changing-Look Quasars in SDSS
• A Description of Quasar Variability Measured Using Repeated SDSS and POSS Imaging
• Fe II Emission in 14 Low-Redshift Quasars: I - Observations
• What the Optical Recombination Lines Can Tell Us About the Broad Line Regions of Active Galactic Nuclei
• The Black Hole Mass - Galaxy Bulge Relationship for QSOs in the SDSS DR3
• Estimating Black Hole Masses in Active Galactic Nuclei Using the MgII 2800 Emission Line
• Discovery of 21 New Changing-look AGNs in Northern Sky
• The Sloan Digital Sky Survey Reverberation Mapping Project: Technical Overview
• The Lick AGN Monitoring Project 2011: Spectroscopic Campaign and Emission-Line Light Curves
• AGN Type-casting: Mrk 590 No Longer Fits the Role
• 1ES 1927+654: An AGN Caught Changing Look on a Timescale of Months
• The Sloan Digital Sky Survey Reverberation Mapping Project: Sample Characterization
• A Mid-IR Selected Changing-Look Quasar and Physical Scenarios for Abrupt AGN Fading
• Changing-Look Quasar Candidates: First Results from Follow-up Spectroscopy of Highly Optically Variable Quasars
• Selecting Quasars by their Intrinsic Variability
• Towards an Understanding of Changing-Look Quasars: An Archival Spectroscopic Search in SDSS
• Systematic Uncertainties in Black Hole Masses Determined from Single Epoch Spectra
• iPTF Discovery of the Rapid "Turn On" of a Luminous Quasar
• Spectral Variability of Quasars in the Sloan Digital Sky Survey. I: Wavelength Dependence
• The Lick AGN Monitoring Project: Recalibrating Single-Epoch Virial Black Hole Mass Estimates
• The Sloan Digital Sky Survey Reverberation Mapping Project: First Broad-line Hbeta and MgII Lags at z>~0.3 from six-Month Spectroscopy
• The Close AGN Reference Survey (CARS) - Mrk 1018 returns to the shadows after 30 years as a Seyfert 1
• A new physical interpretation of optical and infrared variability in quasars
• Quasar Viscosity Crisis
• The Sloan Digital Sky Survey Reverberation Mapping Project: Initial CIV Lag Results from Four Years of Data
• The Mass of the Central Black Hole in the Seyfert Galaxy NGC 4151
• Flare-like variability of the Mg IIλ2800Å emission line in the gamma-ray blazar 3C 454.3
• Broad Hbeta Emission-Line Variability in a Sample of 102 Local Active Galaxies
• The Sloan Digital Sky Survey Reverberation Mapping Project: Ensemble Spectroscopic Variability of Quasar Broad Emission Lines
• Quasar Evolution and the Baldwin Effect in the Large Bright Quasar Survey
• The Sloan Digital Sky Survey Reverberation Mapping Project: Low-Ionization Broad-Line Widths and Implications for Virial Black Hole Mass Estimation
• Slow blue nuclear hypervariables in PanSTARRS-1
• Measuring Quasar Variability with Pan-STARRS1 and SDSS
• The UV and optical Fe II emission lines in type 1 AGNs
• Photoionized HBeta Emission in NGC 5548: It Breathes!
• The structure of the Mg II broad line emitting region in Type 1 AGNs
• CIV Black Hole Mass Measurements with the Australian Dark Energy Survey (OzDES)
• Time delay measurement of Mg II line in CTS C30.10 with SALT
• Swift/UVOT grism monitoring of NGC 5548 in 2013: an attempt at MgII reverberation mapping
• Line and continuum variability of two intermediate-redshift, high-luminosity quasars
• MgII Line Variability of High Luminosity Quasars
• The optical variability of SDSS quasars from multi-epoch spectroscopy. II. color variation
• The Sloan Digital Sky Survey Reverberation Mapping Project: Improving Lag Detection with an Extended Multi-Year Baseline
• SALT long-slit spectroscopy of LBQS 2113-4538: variability of the Mg II and Fe II component
• Relation between the variations in the MgII $\lambda 2798$ emission-line and the 3000 Å continuum
• Chiral effective field theory description of neutrino nucleon-nucleon Bremsstrahlung in supernova matter
• Virilization of the Broad Line Region in Active Galactic Nuclei - connection between shifts and widths of broad emission lines
• Spectral analysis of four 'hypervariable' AGN: a microneedle in the haystack?
• Exploring the Variable Sky with the Sloan Digital Sky Survey

Cited by in corpus (18)

• Improving Damped Random Walk parameters for SDSS Stripe 82 Quasars with Pan-STARRS1
• The Time Domain Spectroscopic Survey: Changing-Look Quasar Candidates from Multi-Epoch Spectroscopy in SDSS-IV
• The Sloan Digital Sky Survey Reverberation Mapping Project: How Broad Emission Line Widths Change When Luminosity Changes
• Exploring Changing-look Active Galactic Nuclei with the Sloan Digital Sky Survey V: First Year Results
• The Sloan Digital Sky Survey Reverberation Mapping Project: Accretion and Broad Emission Line Physics from a Hypervariable Quasar
• Time Delay of MgII Emission Response for the Luminous Quasar HE 0435-4312: Towards Application of High-Accretor Radius-Luminosity Relation in Cosmology
• Time-delay measurement of MgII broad line response for the highly-accreting quasar HE 0413-4031: Implications for the MgII-based radius-luminosity relation
• Extreme Variability and Episodic Lifetime of Quasars
• Probing the Origin of Changing-look Quasar Transitions with Chandra
• High-redshift Extreme Variability Quasars from Sloan Digital Sky Survey Multi-Epoch Spectroscopy
• Consistency study of high- and low-accreting Mg ii quasars: No significant effect of the Fe ii to Mg ii flux ratio on the radius-luminosity relation dispersion
• Demographics of z ~ 6 Quasars in the Black Hole Mass-Luminosity Plane
• Extreme Variability Quasars in Their Various States. I: The sample selection and composite SDSS spectra
• X-ray properties of dust-obscured galaxies with broad optical/UV emission lines
• On the Connection between Supermassive Black Hole and Galaxy Growth in the Reionization Epoch
• Caltech-NRAO Stripe 82 Survey (CNSS). IV. The Birth of Radio-loud Quasar 013815+00
• Behaviour of the MgII 2798AA Line Over the Full Range of AGN Variability
• The SDSS-V Black Hole Mapper Reverberation Mapping Project: Unusual Broad-Line Variability in a Luminous Quasar