The variable and non-variable X-ray absorbers in Compton-thin type-II Active Galactic Nuclei

Abstract

We have conducted an extensive X-ray spectral variability study of a sample of 20 Compton-thin type II galaxies using broad band spectra from XMM-Newton, Chandra, and Suzaku. The aim is to study the variability of the neutral intrinsic X-ray obscuration along the line of sight and investigate the properties and location of the dominant component of the X-ray-obscuring gas. The observations are sensitive to absorption columns of $N_{\mathrm{H}}\sim 10^{20.5-24}\mathrm{c}{\mathrm{m}}^{-2}$ of fully- and partially-covering neutral and/or lowly-ionized gas on timescales spanning days to well over a decade. We detected variability in the column density of the full-covering absorber in 7/20 sources, on timescales of months-years, indicating a component of compact-scale X-ray-obscuring gas lying along the line of sight of each of these objects. Our results imply that torus models incorporating clouds or overdense regions should account for line of sight column densities as low as $\sim$ a few $\times 10^{21}$ cm${}^{-2}$. However, 13/20 sources yielded no detection of significant variability in the full-covering obscurer, with upper limits to $\Delta N_{\mathrm{H}}$ spanning $10^{21-23}$ cm${}^{-2}$. The dominant absorbing media in these systems could be distant, such as kpc-scale dusty structures associated with the host galaxy, or a homogeneous medium along the line of sight. Thus, we find that overall, strong variability in full-covering obscurers is not highly prevalent in Compton-thin type IIs, at least for our sample, in contrast to previous results in the literature. Finally, 11/20 sources required a partial-covering, obscuring component in all or some of their observations, consistent with clumpy near-Compton-thick compact-scale gas.

Accepted for publication in ApJ

References in corpus (115)

• The Leiden/Argentine/Bonn (LAB) Survey of Galactic HI: Final data release of the combined LDS and IAR surveys with improved stray-radiation corrections
• MultiNest: an efficient and robust Bayesian inference tool for cosmology and particle physics
• X-ray spectral modelling of the AGN obscuring region in the CDFS: Bayesian model selection and catalogue
• AGN Black Hole Masses and Bolometric Luminosities
• AGN Dusty Tori: II. Observational Implications of Clumpiness
• Hard X-ray Detector (HXD) on Board Suzaku
• BAT AGN Spectroscopic Survey - V. X-ray properties of the Swift/BAT 70-month AGN catalog
• A Hubble Space Telescope Imaging Survey of Nearby Active Glactic Nuclei
• The AGN Obscuring Torus -- End of the "Doughnut" Paradigm?
• A 4% Geometric Distance to the Galaxy NGC4258 from Orbital Motions in a Nuclear Gas Disk
• Reverberation Measurements of the Inner Radius of the Dust Torus in Nearby Seyfert 1 Galaxies
• A 3 dimensional diagnostic diagram for Seyfert 2s: probing X-ray absorption and Compton thickness
• Three-dimensional radiative transfer modeling of AGN dusty tori as a clumpy two-phase medium
• The nature and origin of Seyfert warm absorbers
• Ubiquitous variability of X-ray absorbing column densities in Seyfert 2 Galaxies
• The close environments of accreting massive black holes are shaped by radiative feedback
• ASCA observations of Seyfert 1 galaxies: I. Data Analysis, Imaging and Timing
• The origin of the Broad Line Region in Active Galactic Nuclei
• X-ray obscuration and obscured AGN in the local universe
• X-ray Spectral Properties of the BAT AGN Sample
• Occultation measurement of the size of the X-ray emitting region in the Active Galactic Nucleus of NGC 1365
• CAIXA: a catalogue of AGN in the XMM-Newton archive III. Excess Variance Analysis
• Bars and Warps traced by the Molecular Gas in the Seyfert 2 Galaxy NGC 1068
• First X-ray-Based Statistical Tests for Clumpy-Torus Models: Eclipse Events from 230 Years of Monitoring of Seyfert AGN
• The soft X-ray/NLR connection: a single photoionized medium?
• The Millennium Galaxy Catalogue: the B-band attenuation of bulge and disc light and the implied cosmic dust and stellar mass densities
• X-ray Spectral Survey with XMM--Newton of a Complete Sample of Nearby Seyfert Galaxies
• Dust in the polar region as a major contributor to the IR emission of AGN
• Dust in active nuclei. II. Powder or gravel?
• On the Disappearance of the Broad-Line Region in Low-Luminosity Agns
• ALMA resolves the torus of NGC 1068: continuum and molecular line emission
• Resolving the obscuring torus in NGC 1068 with the power of infrared interferometry: Revealing the inner funnel of dust
• Radio Sources in Low-Luminosity Active Galactic Nuclei. III. "AGNs" in a Distance-Limited Sample of "LLAGNs"
• MHD Accretion-Disk Winds as X-ray Absorbers in AGNs
• ALMA observations of molecular tori around massive black holes
• On the origin of soft X-rays in obscured AGN: answers from high-resolution spectroscopy with XMM-Newton
• Testing the Unification Model for AGN in the Infrared: are the obscuring tori of Type 1 and 2 Seyferts different?
• Suzaku Observations of Active Galactic Nuclei Detected in the Swift/BAT Survey: Discovery of "New Type" of Buried Supermassive Black Holes
• Radiation-driven Fountain and Origin of Torus around Active Galactic Nuclei
• Warm absorbers in X-rays (WAX), a comprehensive high resolution grating spectral study of a sample of Seyfert galaxies: I. A global view and frequency of occurrence of warm absorbers
• X-ray absorption by Broad Line Region Clouds in Mrk 766
• Chandra-HETGS Observations of the Brightest Flare Seen from Sgr A*
• Dust inflated accretion disc as the origin of the Broad Line Region in Active Galactic Nuclei
• Variable partial covering and a relativistic iron line in NGC 1365
• "Comets" orbiting a black hole
• Deep Silicate absorption features in Compton-thick AGN predominantly arise due to dust in the host galaxy
• The power output of local obscured and unobscured AGN: crossing the absorption barrier with Swift/BAT and IRAS
• The mass of the black hole in Centaurus A from SINFONI AO-assisted integral-field observations of stellar kinematics
• Spectroscopy of the near-nuclear regions of Cygnus A: estimating the mass of the supermassive black hole
• High-Velocity Bipolar Molecular Emission from an AGN Torus
• Parsec-scale dust distributions in Seyfert galaxies - Results of the MIDI AGN snapshot survey
• ALMA Reveals an Inhomogeneous Compact Rotating Dense Molecular Torus at the NGC 1068 Nucleus
• Rapid N_H changes in NGC 4151
• AGN Obscuration and the Unified Model
• How complex is the obscuration in AGN? New clues from the Suzaku monitoring of the X-ray absorbers in NGC7582
• On the 10-micron silicate feature in Active Galactic Nuclei
• Nuclear Disks of Gas and Dust in Early Type Galaxies and the Hunt for Massive Black Holes: Hubble Space Telescope Observations of NGC 6251
• Galaxy gas as obscurer: II. Separating the galaxy-scale and nuclear obscurers of Active Galactic Nuclei
• Exploring the inner region of Type 1 AGNs with the Keck interferometer
• On the relation of optical obscuration and X-ray absorption in Seyfert galaxies
• An absorption event in the X-ray lightcurve of NGC 3227
• Inclination-Dependent Luminosity Function of Spiral Galaxies in the Sloan Digital Sky Survey: Implication for Dust Extinction
• Relativistic Iron K Emission and absorption in the Seyfert 1.9 galaxy MCG-5-23-16
• Infrared Spectral Energy Distributions of Seyfert Galaxies: Spitzer Space Telescope Observations of the 12 micron Sample of Active Galaxies
• Revealing the High Energy Emission from the Obscured Seyfert Galaxy MCG -5-23-16 with Suzaku
• ALMA 0.1-0.2 arcsec resolution imaging of the NGC 1068 nucleus - compact dense molecular gas emission at the putative AGN location
• The Suzaku Observation of the Nucleus of the Radio-Loud Active Galaxy Centaurus A: Constraints on Abundances of the Accreting Material
• The hard X-ray spectrum of NGC 5506 as seen by NuSTAR
• X-ray spectral variability of seven LINER nuclei with XMM-Newton and Chandra data
• The Cocoon Shocks of Cygnus A: Pressures and Their Implications for the Jets and Lobes
• X-QUEST: A Comprehensive X-ray Study of Local ULIRGs and QSOs
• The recent X-ray history of NGC 5506
• The NuSTAR view of reflection and absorption in NGC 7582
• The size of the X-ray emitting region in SWIFT J2127.4+5654 via a broad line region cloud X-ray eclipse
• Host galaxy-active galactic nucleus alignments in the SDSS-DR7
• Simultaneous X-ray and optical observations of true Type 2 Seyfert galaxies
• Suzaku Observations of Moderately Obscured (Compton-thin) Active Galactic Nuclei Selected by Swift/BAT Hard X-ray Survey
• The Hard X-ray Emission of Cen A
• X-ray spectral variability of Seyfert 2 galaxies
• The central parsecs of active galactic nuclei: challenges to the torus
• NuSTAR and XMM-Newton Observations of the Hard X-Ray Spectrum of Centaurus A
• A Long Look At MCG-5-23-16 With NuSTAR: I- Relativistic Reflection And Coronal Properties
• The complex X-ray spectrum of NGC 4507
• Investigating the sensitivity of observed spectral energy distributions to clumpy torus properties in Seyfert galaxies
• Type 2 counterparts of narrow-line Seyfert 1 galaxies
• Twelve and a Half Years of Observations of Centaurus A with RXTE
• An Occultation Event in Centaurus A and the Clumpy Torus Model
• A multiwavelength map of the nuclear region of NGC7582
• Emission Line Properties of Seyfert Galaxies in the 12 Micron Sample
• A rapid occultation event in NGC 3227
• AGN obscuration from winds: from dusty infrared-driven to warm and X-ray photoionized
• A Low-Flux State in IRAS 00521-7054 seen with NuSTAR and XMM-Newton: Relativistic Reflection and an Ultrafast Outflow
• The Seyfert 2 galaxy NGC 2110: hard X-ray emission observed by NuSTAR and variability of the iron K$\alpha$ line
• Probing the accretion disk and central engine structure of NGC4258 with Suzaku and XMM-Newton observations
• Suzaku view of X-ray Spectral Variability of the Radio Galaxy Centaurus A : Partial Covering Absorber, Reflector, and Possible Jet Component
• An XMM-Newton Observation of the Seyfert 2 Galaxy NGC 6300. I. The Nucleus
• X-ray imaging of the ionisation cones in NGC 5252
• NuSTAR observations of the powerful radio-galaxy Cygnus A
• The hard X-ray spectrum of the Seyfert galaxy IRAS 18325-5926: cool corona, reflection from an ionized disk and variable iron K emission
• Wide-band spectroscopy of the Compton thick Seyfert 2 galaxy Mrk 3 with Suzaku
• On the nature of X-ray absorption in Seyfert 2 galaxies
• Transient and Highly Polarized Double-Peaked H-alpha Emission in the Seyfert 2 Nucleus of NGC 2110
• Evidence for Non-Hydrostatic Gas Motions in the Hot ISM of Centaurus A
• Evidence for Relativistic Disk Reflection in the Seyfert 1h Galaxy/ULIRG IRAS 05189-2524 Observed by NuSTAR and XMM-Newton
• NGC 2992 in an X-ray high state observed by XMM: Response of the Relativistic Fe K$\alpha$ Line to the Continuum
• The X-ray variability of Seyfert 1.8/1.9 galaxies
• Probing the unified model in NGC 7314
• BeppoSAX Observations of the Seyfert-2 Galaxies NGC 7172 and ESO 103-G35
• Suzaku observation of IRAS 00521-7054, a peculiar type-II AGN with a very broad feature at 6 keV
• High-resolution mapping of the physical conditions in two nearby active galaxies based on 12CO(1-0), (2-1) and (3-2) lines
• The final verdict by XMM-Newton: the X-ray obscured Seyfert galaxy NGC5506 has a broad Fe K-alpha line
• BeppoSAX view of NGC 526A: a Seyfert 1.9 galaxy with a flat spectrum
• RXTE monitoring of Centaurus A
• The variable ionized absorber in the Seyfert 2 Mrk 348
• The Suzaku View of the Disk-Jet Connection in the Low Excitation Radio Galaxy NGC 6251

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• The properties of the AGN torus as revealed from a set of unbiased NuSTAR observations
• Compton-Thick AGN in the NuSTAR era VI: The observed Compton-thick fraction in the Local Universe
• Systematic Study of AGN Clumpy Tori with Broadband X-ray Spectroscopy: Updated Unified Picture of AGN Structure
• Infrared Spectral Energy Distribution and Variability of Active Galactic Nuclei: Clues to the Structure of Circumnuclear Material
• Extreme ultra-soft X-ray variability in an eROSITA observation of the Narrow-Line Seyfert 1 Galaxy 1H 0707-495
• The dust-gas AGN torus as constrained from X-ray and mid-infrared observations
• Hard X-Ray to Radio Multiwavelength SED Analysis of Local U/LIRGs in GOALS Sample with Self-consistent AGN Model Including Polar-dust Component
• The Black Hole-Galaxy Connection: Interplay between Feedback, Obscuration, and Host Galaxy Substructure
• Supermassive Black Hole Winds in X-rays -- SUBWAYS. III. A population study on ultra-fast outflows
• Hydrogen Column Density Variability in a Sample of Local Compton-Thin AGN
• Inferring the morphology of AGN torus using X-ray spectra: A reliability study
• Compton-thick AGN in the NuSTAR Era. IX. A Joint NuSTAR and XMM-Newton Analysis of Four Local AGN
• Properties of the Obscuring Torus in NGC 1052 from Multi-epoch Broadband X-ray Spectroscopy
• A multi-epoch X-ray study of the nearby Seyfert 2 galaxy NGC 7479: Linking column density variability to the torus geometry
• An X-ray spectral study of the origin of reflection features in bare Seyfert 1 galaxy ESO 511--G030
• The lively accretion disk in NGC 2992. II. The 2019/2021 X-ray monitoring campaigns
• Spontaneous Formation of Outflows Powered by Rotating Magnetized Accretion Flows in a Galactic Center
• Dust Dynamics in AGN Winds: A New Mechanism For Multiwavelength AGN Variability
• The NuSTAR view of the changing look AGN ESO 323-G77
• A hard look at the X-ray spectral variability of NGC 7582
• A weakening Compton hump and soft X-ray excess detected in the Seyfert-1 galaxy MCG-02-58-22
• Are Compton-thin AGNs Globally Compton Thin?
• A Highly Accreting Low-Mass Black Hole Hidden in the Dust: Suzaku and NuSTAR observations of the NLS1 Mrk 1239
• A Multi-Wavelength Characterization of the Obscuring Medium at the Center of NGC 6300
• A closer look at NGC 7314 nuclear region: a multiwavelength analysis of the Seyfert nucleus and its surroundings
• Hot accretion flows in low-luminosity active galactic nuclei in NGC 4258 and NGC 7213
• A radio, optical, UV and X-ray view of the enigmatic changing look Active Galactic Nucleus 1ES~1927+654 from its pre- to post-flare states
• The properties of the obscuring material of an AGNs sample from mid-IR and X-ray simultaneous fitting