An X-ray fading, UV brightening QSO at $z\approx 6$

Abstract

Explaining the existence of $\gtrsim 10^8{\mathrm{M}}_{\odot }$ SMBHs at $z>6$ is a persistent challenge to modern astrophysics. Multi-wavelength observations of $z\gtrsim 6$ QSOs reveal that, on average, their accretion physics is similar to that of their counterparts at lower redshift. However, QSOs showing properties that deviate from the general behavior can provide useful insights into the physical processes responsible for the rapid growth of SMBHs in the early universe. We present X-ray (XMM-Newton, 100 ks) follow-up observations of a $z\approx 6$ QSO, J1641+3755, which was found to be remarkably X-ray bright in a 2018 Chandra dataset. J1641+3755 is not detected in the 2021 XMM-Newton observation, implying that its X-ray flux decreased by a factor $\gtrsim 7$ on a notably short timescale (i.e., $\approx 115$ rest-frame days), making it the $z>4$ QSO with the largest variability amplitude. We also obtained rest-frame UV spectroscopic and photometric data with textit{LBT}, and compared them with archival datasets. Surprisingly, we found that J1641+3755 became brighter in the rest-frame UV band from 2003 to 2016, while no strong variation occurred from 2016 to 2021. Multiple narrow absorption features are detected in its rest-frame UV spectrum, and several of them can be associated with an intervening system at $z=5.67$. The variability properties of J1641+3755 can be due to intrinsic variations of the accretion rate, a small-scale obscuration event, gravitational lensing due to an intervening object, or an unrelated X-ray transient in a foreground galaxy in 2018. Accounting for all of the $z>6$ QSOs with multiple X-ray observations separated by $>10$ rest-frame days, we found an enhancement of strongly (i.e., by a factor $>3$) X-ray variable objects compared to QSOs at later cosmic times. This finding may be related to the physics of fast accretion in high-redshift QSOs.

arXiv comment14 pages. Accepted for publication on A&A

References in corpus (92)

• Astropy: A Community Python Package for Astronomy
• Planck 2015 results. XIII. Cosmological parameters
• Binary companions of evolved stars in APOGEE DR14: Search method and catalog of ~5,000 companions
• The Leiden/Argentine/Bonn (LAB) Survey of Galactic HI: Final data release of the combined LDS and IAR surveys with improved stray-radiation corrections
• Overview of the DESI Legacy Imaging Surveys
• An 800-million-solar-mass black hole in a significantly neutral Universe at redshift 7.5
• A Survey of z>5.8 Quasars in the Sloan Digital Sky Survey I: Discovery of Three New Quasars and the Spatial Density of Luminous Quasars at z~6
• An ultra-luminous quasar with a twelve-billion-solar-mass black hole at redshift 6.30
• An Empirical Ultraviolet Template for Iron Emission in Quasars as Derived from I Zw 1
• The X-ray-to-Optical Properties of Optically-Selected Active Galaxies Over Wide Luminosity and Redshift Ranges
• A Luminous Quasar at Redshift 7.642
• The Discovery of the First "Changing Look" Quasar: New Insights into the Physics & Phenomenology of AGN
• Bolometric luminosities and Eddington ratios of X-ray selected Active Galactic Nuclei in the XMM-COSMOS survey
• The X-ray Properties of the Most-Luminous Quasars from the Sloan Digital Sky Survey
• The Pan-STARRS1 distant z>5.6 quasar survey: more than 100 quasars within the first Gyr of the universe
• The XMM-Newton serendipitous survey IX. The fourth XMM-Newton serendipitous source catalogue
• Universal bolometric corrections for AGN over 7 luminosity decades
• Eddington-limited accretion and the black hole mass function at redshift 6
• Physical properties of 15 quasars at $z\gtrsim 6.5$
• An ALMA [CII] survey of 27 quasars at z>5.94
• Four quasars above redshift 6 discovered by the Canada-France High-z Quasar Survey
• Super-Eddington Accretion Disks around Supermassive black Holes
• The tight relation between X-ray and ultraviolet luminosity of quasars
• The Hard X-ray Spectral Slope as an Accretion-Rate Indicator in Radio-Quiet Active Galactic Nuclei
• Black hole masses and enrichment of z ~ 6 SDSS quasars
• A statistical relation between the X-ray spectral index and Eddington ratio of active galactic nuclei in deep surveys
• Black hole mass estimates and emission-line properties of a sample of redshift z>6.5 quasars
• Tidal disruption rate of stars by spinning supermassive black holes
• Bright [CII] and dust emission in three z>6.6 quasar host galaxies observed by ALMA
• Gemini GNIRS near-infrared spectroscopy of 50 quasars at z>~5.7
• The VVDS data reduction pipeline: introducing VIPGI, the VIMOS Interactive Pipeline and Graphical Interface
• The Sloan Digital Sky Survey Reverberation Mapping Project: Velocity Shifts of Quasar Emission Lines
• X-ray Insights into the Nature of PHL 1811 Analogs and Weak Emission-Line Quasars: Unification with a Geometrically Thick Accretion Disk?
• Detection of atomic carbon [CII] 158 micron and dust emission from a z=7.1 quasar host galaxy
• The destruction and recreation of the X-ray corona in a changing-look Active Galactic Nucleus
• A global view of the inner accretion and ejection flow around super massive black holes: radiation driven accretion disk winds in a physical context
• The Opacity of the Intergalactic Medium Measured Along Quasar Sightlines at $z\sim 6$
• Quasars as standard candles I: The physical relation between disc and coronal emission
• The young stellar population in M17 revealed by Chandra
• Constraining the radio-loud fraction of quasars at z>5.5
• Self-shadowing Effects of Slim Accretion Disks in Active Galactic Nuclei: Diverse Appearance of the Broad-line Region
• A Chandra Search for Coronal X Rays from the Cool White Dwarf GD 356
• The X-SHOOTER/ALMA sample of Quasars in the Epoch of Reionization. I. NIR spectral modeling, iron enrichment and broad emission line properties
• The X-ray properties of $z>6$ quasars: no evident evolution of accretion physics in the first Gyr of the Universe
• Ultraluminous X-Ray Sources
• The Discovery of a Gravitationally Lensed Quasar at z = 6.51
• Probing the interstellar medium and star formation of the Most Luminous Quasar at z=6.3
• The X-ray properties of z$\sim$6 luminous quasars
• The WISSH Quasars Project III. X-ray properties of hyper-luminous quasars
• The first blazar observed at z>6
• Observational Signatures of High-Redshift Quasars and Local Relics of Black Hole Seeds
• The X-ray Spectral Properties and Variability of Luminous High-Redshift Active Galactic Nuclei
• Gravitational Lensing Size Scales for Quasars
• New Constraints on Quasar Evolution: Broad Line Velocity Shifts over $1.5\lesssim z\lesssim 7.5$
• CO (2-1) Line Emission in Redshift 6 Quasar Host Galaxies
• AGN X-ray variability in the XMM-COSMOS survey
• Revealing the Accretion Physics of Supermassive Black Holes at Redshift z~7 with Chandra and Infrared Observations
• QSO obscuration at high redshift ($z\gtrsim 7$): Predictions from the BlueTides simulation
• Tracing the accretion history of supermassive Black Holes through X-ray variability: results from the Chandra Deep Field-South
• Caught in the Act; Chandra Observations of Microlensing of the Radio-Loud Quasar MG J0414+0534
• Exploratory Chandra Observations of the Three Highest Redshift Quasars Known
• Quasars as standard candles II: The non linear relation between UV and X-ray emission at high redshifts
• On the Observational Difference Between the Accretion Disk-Corona Connections among Super- and Sub-Eddington Accreting Active Galactic Nuclei
• Ensemble X-ray variability of Active Galactic Nuclei. II. Excess Variance and updated Structure Function
• The X-Ray Variability of a Large, Serendipitous Sample of Spectroscopic Quasars
• X-ray Monitoring of Gravitational Lenses With Chandra
• A Consistent Picture Emerges: A Compact X-ray Continuum Emission Region in the Gravitationally Lensed Quasar SDSS J0924+0219
• A long term study of AGN X-ray variability. Structure function analysis on a ROSAT-XMM quasar sample
• SRG/eROSITA uncovers the most X-ray luminous quasar at z>6
• Mock catalogs for the extragalactic X-ray sky: simulating AGN surveys with Athena and with the AXIS probe
• Insights on the X-ray weak quasar phenomenon from XMM-Newton monitoring of PHL 1092
• The frequency of extreme X-ray variability of radio-quiet quasars
• The 500 ks Chandra observation of the z = 6.31 QSO SDSS J1030+0524
• X-ray Observations of a $z\sim 6.2$ Quasar/Galaxy Merger
• An Extreme X-ray Variability Event of a Weak-Line Quasar
• Sensitive Chandra coverage of a representative sample of weak-line quasars: revealing the full range of X-ray properties
• Microlensing of the X-ray, UV and optical emission regions of quasars: Simulations of the time-scales and amplitude variations of microlensing events
• X-ray properties of z>6.5 quasars
• The X-ray Spectrum of the z=6.30 QSO SDSS J1030+0524
• X-ray observation of ULAS J1120+0641, the most distant quasar at z=7.08
• XMM-Newton observations of the extremely X-ray luminous quasar CFHQS J142952+544717=SRGE J142952.1+544716 at redshift z=6.18
• SDSS J075101.42+291419.1: A Super-Eddington Accreting Quasar with Extreme X-ray Variability
• Direct observation of an extended X-ray jet at $z$=6.1
• Chandra and Magellan/FIRE follow-up observations of PSO167-13: an X-ray weak QSO at $z=6.515$
• SIPGI: an interactive pipeline for spectroscopic data reduction
• Exploratory Chandra observation of the ultraluminous quasar SDSS J010013.02+280225.8 at redshift 6.30
• Prescriptions for Correcting Ultraviolet-Based Redshifts for Luminous Quasars at High Redshift
• XMM-Newton observation of the ultraluminous quasar SDSS J010013.02+280225.8 at redshift 6.326
• Exploratory X-ray Monitoring of Luminous Radio-Quiet Quasars at High Redshift: No Evidence for Evolution in X-ray Variability
• Chandra measurement of the X-ray spectrum of a quasar at z=5.99
• Amplification and variability of the AGN X-ray emission due to microlensing
• Exploratory X-Ray Monitoring of Luminous Radio-Quiet Quasars at High Redshift: Extended Time-Series Analyses and Stacked Imaging Spectroscopy

Cited by in corpus (8)

• HYPerluminous quasars at the Epoch of ReionizatION (HYPERION). A new regime for the X-ray nuclear properties of the first quasars
• Fast SMBH growth in the SPT2349--56 protocluster at $z=4.3$
• The SRG/eROSITA All-Sky Survey: X-ray beacons at late cosmic dawn
• A powerful (and likely young) radio-loud quasar at z=5.3
• The ALPINE-ALMA [CII] survey: double stellar population and AGN activity in a galaxy at $z\sim 5.5$
• Discovery and characterization of 25 new quasars at 4.6 < z < 6.9 from wide-field multi-band surveys
• Radio Scrutiny of the X-ray-Weak Tail of Low-Mass Active Galactic Nuclei: A Novel Signature of High-Eddington Accretion?
• Intervening nuclear obscuration changing the X-ray look of the $z\approx 6$ QSO CFHQS J164121+375520