X-ray Unveiling Events in a z~1.6 Active Galactic Nucleus in the 7 Ms Chandra Deep Field-South

Abstract

We investigate the extreme X-ray variability of a z = 1.608 active galactic nucleus in the 7 Ms Chandra Deep Field-South (XID 403), which showed two significant X-ray brightening events. In the first event, XID 403 brightened by a factor of $>2.5$ in $\lesssim 6.1$ rest-frame days in the observed-frame 0.5-5 keV band. The event lasted for $\approx 5.0\text{-}7.3$ days, and then XID 403 dimmed by a factor of $>6.0$ in $\lesssim 6.1$ days. After $\approx 1.1\text{-}2.5$ years in the rest frame (including long observational gaps), it brightened again with the 0.5-5 keV flux increasing by a factor of $>12.6$. The second event lasted over 251 days and the source remained bright until the end of the 7 Ms exposure. The spectrum is a steep power law (photon index $\Gamma =2.8\pm 0.3$) without obscuration during the second outburst, and the rest-frame 2-10 keV luminosity reaches $1.5_{-0.5}^{+0.8}\times 10^{43}$ erg s${}^{-1}$; there is no significant spectral evolution within this epoch. The infrared-to-UV spectral energy distribution of XID 403 is dominated by the host galaxy. There is no significant optical/UV variability and $R$-band (rest-frame $\approx 2500$ $\unicode{xC5}$) brightening contemporaneous with the X-ray brightening. The extreme X-ray variability is likely due to two X-ray unveiling events, where the line of sight to the corona is no longer shielded by high-density gas clumps in a small-scale dust-free absorber. XID 403 is probably a high-redshift analog of local narrow-line Seyfert 1 galaxies, and the X-ray absorber is a powerful accretion-disk wind. On the other hand, we cannot exclude the possibility that XID 403 is an unusual candidate for tidal disruption events.

23 pages, 9 figures, accepted for publication in ApJ

References in corpus (68)

• The James Webb Space Telescope
• HI4PI: A full-sky HI survey based on EBHIS and GASS
• The Zwicky Transient Facility: Data Processing, Products, and Archive
• The Near-Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope I. Overview of the instrument and its capabilities
• The X-ray-to-Optical Properties of Optically-Selected Active Galaxies Over Wide Luminosity and Redshift Ranges
• The Chandra Deep Field-South Survey: 7 Ms Source Catalogs
• Tidal Disruption Events
• The Discovery of the First "Changing Look" Quasar: New Insights into the Physics & Phenomenology of AGN
• The X-ray Properties of the Most-Luminous Quasars from the Sloan Digital Sky Survey
• The diversity of quasars unified by accretion and orientation
• The Dark Energy Survey Data Release 2
• X-CIGALE: fitting AGN/galaxy SEDs from X-ray to infrared
• The Hard X-ray Spectrum as a Probe for Black-Hole Growth in Radio-Quiet Active Galactic Nuclei
• The FourStar Galaxy Evolution Survey (ZFOURGE): ultraviolet to far-infrared catalogs, medium-bandwidth photometric redshifts with improved accuracy, stellar masses, and confirmation of quiescent galaxies to z~3.5
• X-ray Quasi-Periodic Eruptions from two previously quiescent galaxies
• Fitting AGN/galaxy X-ray-to-radio SEDs with CIGALE and improvement of the code
• Mean Spectral Energy Distributions and Bolometric Corrections for Luminous Quasars
• X-ray Insights into the Nature of PHL 1811 Analogs and Weak Emission-Line Quasars: Unification with a Geometrically Thick Accretion Disk?
• The destruction and recreation of the X-ray corona in a changing-look Active Galactic Nucleus
• X-ray Absorption and Reflection in Active Galactic Nuclei
• The young stellar population in M17 revealed by Chandra
• Properties of AGN coronae in the NuSTAR era II: hybrid plasma
• The XMM-Newton long look of NGC 1365: uncovering of the obscured X-ray source
• A likely decade-long sustained tidal disruption event
• XMM-Newton observations of the Narrow-Line Seyfert 1 galaxy Mrk 335 in an historical low X-ray flux state
• Live to die another day: the rebrightening of AT2018fyk as a repeating partial tidal disruption event
• Discovery of the Narrow-Line Seyfert 1 galaxy Mkn 335 in an historical low X-ray flux state
• Long-Term X-ray Variability of Typical Active Galactic Nuclei in the Distant Universe
• Tracing the accretion history of supermassive Black Holes through X-ray variability: results from the Chandra Deep Field-South
• On the Observational Difference Between the Accretion Disk-Corona Connections among Super- and Sub-Eddington Accreting Active Galactic Nuclei
• The 450 days X-ray monitoring of the changing-look AGN 1ES 1927+654
• Reverberation Measurements of the Inner Radii of the Dust Tori in Quasars
• X-ray properties of TDEs
• The correlations between optical/UV broad lines and X-ray emission for a large sample of quasars
• The Chandra Deep Fields: Lifting the Veil on Distant Active Galactic Nuclei and X-Ray Emitting Galaxies
• Distinguishing Tidal Disruption Events from Impostors
• Radiation pressure confinement - IV. Application to broad absorption line outflows
• The XMM-SERVS survey: XMM-Newton point-source catalogs for the W-CDF-S and ELAIS-S1 fields
• Polar dust obscuration in broad-line active galaxies from the XMM-XXL field
• Piercing Through Highly Obscured and Compton-thick AGNs in the Chandra Deep Fields: I. X-ray Spectral and Long-term Variability Analyses
• X-ray flares from the stellar tidal disruption by a candidate supermassive black hole binary
• Evolution of a Relativistic Outflow and X-ray Corona in the Extreme Changing-Look AGN 1ES 1927+654
• AT2019 avd: A tidal disruption event with a two-phase evolution
• Deepest view of AGN X-ray variability with the 7 Ms Chandra Deep Field-South survey
• An Extreme X-ray Variability Event of a Weak-Line Quasar
• Optically variable active galactic nuclei in the 3 yr VST survey of the COSMOS field
• Sensitive Chandra coverage of a representative sample of weak-line quasars: revealing the full range of X-ray properties
• SUDARE-VOICE variability-selection of Active Galaxies in the Chandra Deep Field South and the SERVS/SWIRE region
• Long-term and multi-wavelength evolution of a changing-look AGN Mrk 1018
• Location and energetics of the ultra-fast outflow in PG 1448+273
• SDSS J075101.42+291419.1: A Super-Eddington Accreting Quasar with Extreme X-ray Variability
• PHL 1092 as a transient extreme X-ray weak quasar
• Further evidence to support a tidal disruption event in the changing-look AGN SDSS J0159
• Light Curves of Partial Tidal Disruption Events
• Transient obscuration event captured in NGC~3227 II. Warm absorbers and obscuration events in archival XMM-Newton and NuSTAR observations
• NuSTAR Observations of Intrinsically X-ray Weak Quasar Candidates: An Obscuration-Only Scenario
• On the relation between hard X-ray photon index versus accretion rate for super-Eddington accreting quasars
• SDSS J0159 as an outlier in the Mbh-sigma space: further clues to support a central tidal disruption event?
• The Rapidly Spinning Intermediate-Mass Black Hole 3XMM J150052.0+015452
• A Rapid and Large-Amplitude X-ray Dimming Event in a z ~ 2.6 Radio-Quiet Quasar
• A Partial Eclipse of the Heart: The Absorbed X-ray Low State in Mrk 1048
• Follow-up Observations of the Prolonged, super-Eddington, Tidal Disruption Event Candidate 3XMM~J150052.0+015452: the Slow Decline Continues
• Transient obscuration event captured in NGC 3227 III. Photoionization modeling of the X-ray obscuration event in 2019
• The Hubble Catalog of Variables (HCV)
• The XMM deep survey in the CDF-S. X. X-ray variability of bright sources
• X-ray Selected Narrow-Line Active Galactic Nuclei in the COSMOS Field: Nature of Optically Dull Active Galactic Nuclei
• Absorption Variability of the Highly Obscured Active Galactic Nucleus NGC 4507
• Swift, NuStar and XMM-Newton observations of the NLS1 galaxy RX J2317.8-4422 in an extreme X-ray low flux state

Cited by in corpus (2)

• Intervening nuclear obscuration changing the X-ray look of the $z\approx 6$ QSO CFHQS J164121+375520
• The Faintest, Extremely Variable X-ray Tidal Disruption Event from a Supermassive Black Hole Binary?