A 3 dimensional diagnostic diagram for Seyfert 2s: probing X-ray absorption and Compton thickness

Abstract

We present and discuss a "3-dimensional" diagnostic diagram for Seyfert2 galaxies obtained by means of X-ray and [OIII] data on a large sample of objects (reported in the Appendix). The diagram shows the Kalpha iron line equivalent width as a function of both the column density derived from the photoelectric cutoff and the 2-10 keV flux normalized to the [OIII] optical line flux (the latter corrected for extinction and assumed to be a true indicator of the source intrinsic luminosity). We find that the hard X-ray properties of type 2 objects depend on a single parameter, the absorbing column density along the line of sight,in accordance with the unified model. The diagram can be used to identify Compton thick sources and to isolate and study peculiar objects. From this analysis we have obtained a column density distribution of Seyfert 2 galaxies which is thought to be a good approximation of the real distribution. A large population of heavily absorbed objects is discovered, including many Compton thick candidates. Our results indicate that the mean Log Nh/cm^(-2)in type 2 Seyferts is 23.5 and that as much as 23-30% of sources have Nh > 10^24 cm^(-2).

33 pages, 3 figures, to be published in ApJ Supp

References in corpus (18)

• A Search for "Dwarf" Seyfert Nuclei. III. Spectroscopic Parameters and Properties of the Host Galaxies
• The Contribution of the Obscuring Torus to the X--Ray Spectrum of Seyfert Galaxies: A Test for the Unification Model
• ASCA observations of Seyfert 1 galaxies: I. Data Analysis, Imaging and Timing
• The Extended 12 Micron Galaxy Sample
• ASCA observations of type-2 Seyfert galaxies: II. The Importance of X-ray Scattering and Reflection
• The iron K line complex in NGC1068: implications for X-ray reflection in the nucleus
• ASCA observations of type-2 Seyfert Galaxies. III. Orientation and X-ray Absorption
• ASCA PV observations of the Seyfert 2 galaxy NGC 4388: the obscured nucleus and its X-ray emission
• ROSAT HRI observations of IRAS P09104+4109: a massive cooling flow
• Detection of an iron K Emission Line from the LINER NGC 4579
• Is the X-ray spectrum of the Seyfert 2 galaxy NGC5252 intrinsically flat?
• ASCA Observations of the Seyfert 2 Galaxy NGC 7582: An Obscured and Scattered View of the Hidden Nucleus
• The X-ray spectrum and variability of the Seyfert 2 Galaxy NGC7172
• The Ionization Fraction in the Obscuring `Torus' of an Active Galactic Nucleus
• On the nature of the X-ray absorption in the Seyfert 2 galaxy NGC 4507
• X-ray absorption in the strong FeII narrow-line Seyfert 1 galaxy Mrk 507
• AXJ1749+684: a narrow emission-line galaxy with a flat X-ray spectrum
• Optical Identification of the Hardest X-ray Source in the ASCA Large Sky Survey

Cited by in corpus (342)

• A fundamental plane of black hole activity
• Nuclear Activity in Nearby Galaxies
• Spectral Energy Distributions of Hard X-ray selected AGNs in the XMDS Survey
• Present-Day Growth of Black Holes and Bulges: the SDSS Perspective
• The Chandra Deep Field-North Survey. XIII. 2 Ms Point-Source Catalogs
• The distribution of absorbing column densities among Seyfert 2 galaxies
• Dust Emission from Active Galactic Nuclei
• Observations of Ultraluminous Infrared Galaxies with the Infrared Spectrograph on the Spitzer Space Telescope II: The IRAS Bright Galaxy Sample
• The X-ray Spectral Properties of SCUBA Galaxies
• Dust in active nuclei. I. Evidence for "anomalous" properties
• Candidate Type II Quasars from the Sloan Digital Sky Survey: I. Selection and Optical Properties of a Sample at 0.3<Z<0.83
• Ubiquitous variability of X-ray absorbing column densities in Seyfert 2 Galaxies
• On the X-ray, optical emission line and black hole mass properties of local Seyfert galaxies
• Resolving the mid-infrared cores of local Seyferts
• The relation between AGN hard X-ray emission and mid-infrared continuum from ISO spectra: Scatter and unification aspects
• Narrow-line region gas kinematics of 24,264 optically-selected AGN: the radio connection
• Swift BAT Survey of AGN
• A rapidly spinning supermassive black hole at the centre of NGC 1365
• The Fall of AGN and the Rise of Star-Forming Galaxies: A Close Look at the Chandra Deep Field X-ray Number Counts
• The Relationship of Hard X-ray and Optical Line Emission in Low Redshift Active Galactic Nuclei
• X-ray obscuration and obscured AGN in the local universe
• The Megamaser Cosmology Project. III. Accurate Masses of Seven Supermassive Black Holes in Active Galaxies with Circumnuclear Megamaser Disks
• X-ray Spectral Survey with XMM--Newton of a Complete Sample of Nearby Seyfert Galaxies
• A New Diagnostic of Active Galactic Nuclei: Revealing Highly-Absorbed Systems at Redshift>0.3
• Accretion and star formation rates in low redshift type-II active galactic nuclei
• Chandra and Spitzer unveil heavily obscured quasars in the SWIRE/Chandra Survey
• The subarcsecond mid-infrared view of local active galactic nuclei: II. The mid-infrared--X-ray correlation
• The bolometric luminosity of type 2 AGN from extinction-corrected [OIII]: no evidence for Eddington-limited sources
• The Chandra Deep Field North Survey. VI. The Nature of the Optically Faint X-ray Source Population
• Nuclear star formation activity and black hole accretion in nearby Seyfert galaxies
• Hidden Broad Line Seyfert 2 Galaxies in the CfA and 12micron Samples
• The Chandra Deep Field-North Survey. XIV. X-ray detected Obscured AGNs and Starburst Galaxies in the Bright Submm Source Population
• X-ray Properties of LINERs and Low-luminosity Seyfert Galaxies Observed with ASCA. I. Observations and Results
• Unabsorbed Seyfert 2 galaxies
• Empirical diagnostics of the starburst-AGN connection
• Suzaku Observations of Active Galactic Nuclei Detected in the Swift/BAT Survey: Discovery of "New Type" of Buried Supermassive Black Holes
• Obscured AGN and the X-ray, Optical and Far-Infrared Number Counts of AGN in the GOODS Fields
• The Unified Model & Evolution of Active Galaxies: Implications from a Spectropolarimetric Study
• Host Galaxy Properties of the Swift BAT Ultra Hard X-ray Selected AGN
• X-ray Absorption and Reflection in Active Galactic Nuclei
• Molecular gas streamers feeding and obscuring the active nucleus of NGC1068
• Quiescent Galaxies in the 3D-HST Survey: Spectroscopic Confirmation of a Large Number of Galaxies with Relatively Old Stellar Populations at z~2
• Chandra Detection of a TypeII Quasar at z=3.288
• Compton Thick AGN: the dark side of the X-ray background
• Deep Silicate absorption features in Compton-thick AGN predominantly arise due to dust in the host galaxy
• C-GOALS: Chandra observations of a complete sample of luminous infrared galaxies from the IRAS Revised Bright Galaxy Survey
• Seyfert galaxies in the local Universe (z$\le$ 0.1): the average X-ray spectrum as seen by $BeppoSAX$
• New Indicators for AGN Power: The Correlation Between [O IV] lambda 25.89 micron and Hard X-ray Luminosity for Nearby Seyfert Galaxies
• Elusive Active Galactic Nuclei
• Spitzer IRS spectra of a large sample of Seyfert galaxies: a variety of infrared SEDs in the local AGN population
• Unveiling the nature of INTEGRAL objects through optical spectroscopy. V. Identification and properties of 21 southern hard X-ray sources
• Reliable Identification of Compton-thick Quasars at z~2: Spitzer Mid-IR spectroscopy of HDF-oMD49
• The Second INTEGRAL AGN Catalogue
• Connecting the cosmic infrared background to the X-ray background
• The Lack of BLR in Low Accretion Rate AGN as Evidence of their Origin in the Accretion Disk
• A Chandra Survey of the Nearest ULIRGs: Obscured AGN or Super-Starbursts?
• The Toroidal Obscuration of Active Galactic Nuclei
• AGN Obscuration and the Unified Model
• A New Population of Compton-Thick AGN Identified Using the Spectral Curvature Above 10 keV
• Widespread and Hidden Active Galactic Nuclei in Star-Forming Galaxies at Redshift > 0.3
• Isotropic Luminosity Indicators in a Complete AGN Sample
• XMM-Newton observations expose AGN in apparently normal galaxies
• Candidate Type II Quasars from the Sloan Digital Sky Survey: II. From Radio to X-Rays
• The mid IR -- hard X-ray correlation in AGN and its implications for dusty torus models
• RXTE all-sky slew survey. Catalog of X-ray sources at |b|>10deg
• The fraction of Compton-thick sources in an INTEGRAL complete AGN sample
• Chandra X-ray and Hubble Space Telescope Imaging of Optically Selected kiloparsec-Scale Binary Active Galactic Nuclei I. Nature of the Nuclear Ionizing Sources
• Unveiling the nature of INTEGRAL objects through optical spectroscopy. VI. A multi-observatory identification campaign
• The XMM-Newton wide-field survey in the COSMOS field. IV: X-ray spectral properties of Active Galactic Nuclei
• The Correlation of Narrow Line Emission and X-ray Luminosity in Active Galactic Nuclei
• N-band Imaging of Seyfert Nuclei and the MIR-X-ray correlation
• Compton thick active galactic nuclei in Chandra surveys
• The Link Between the Hidden Broad Line Region and the Accretion Rate in Seyfert 2 Galaxies
• Mid-infrared properties of nearby low-luminosity AGN at high angular resolution
• Mergers Do Trigger AGNs out to z $\sim$ 0.6
• Connecting Galaxy Evolution, Star Formation and the X-ray Background
• AEGIS: Demographics of X-ray and Optically Selected AGNs
• ISO spectroscopy of star formation and active nuclei in the luminous infrared galaxy NGC 6240
• Jet directions in Seyfert galaxies: Radio continuum imaging data
• Uncovering obscured luminous AGN with WISE
• Reflection in Seyfert Galaxies and the Unified Model of AGN
• The X-ray to [Ne V]3426 flux ratio: discovering heavily obscured AGN in the distant Universe
• The 60-month all-sky BAT Survey of AGN and the Anisotropy of Nearby AGN
• Indicators of Intrinsic AGN Luminosity: a Multi-Wavelength Approach
• X-ray spectral analyses of AGNs from the 7Ms Chandra Deep Field-South survey: the distribution, variability, and evolution of AGN's obscuration
• XMM-Newton observations of the Lockman Hole IV: spectra of the brightest AGN
• Obscuration and Origin of Nuclear X-ray emission in FR I Radio Galaxies
• The XMM-Newton HBS28 sample: studying the obscuration in hard X-ray selected AGNs
• BAT X-ray Survey - III: X-ray Spectra and Statistical Properties
• The X-ray spectra of optically selected Seyfert 2 galaxies. Are there any Sy2 galaxies with no absorption?
• The Seyfert-Starburst Connection in X-rays. II. Results and Implications
• The Unified Model of Active Galactic Nuclei: II. Evolutionary Connection
• The X-ray spectral properties of the AGN population in the XMM-Newton bright serendipitous survey
• Far-infrared line spectra of active galaxies from the Herschel/PACS Spectrometer: the complete database
• Extragalactic H_2O masers and X-ray absorbing column densities
• Compton thick AGN in the NuSTAR era
• Emission Line Properties of Seyfert 2 Nuclei
• The non-stellar infrared continuum of Seyfert galaxies
• An XMM-Newton spectral survey of 12 micron selected galaxies. II. Implications for AGN selection and unification
• Investigating on the nuclear obscuration in two types of Seyfert 2 galaxies
• NuSTAR unveils a Compton-thick Type 2 quasar in Mrk 34
• Hard X-ray Emission and the Ionizing Source in LINERs
• Restframe Optical Spectroscopic Classifications for Submillimeter Galaxies
• XMM-Newton observations of Seyfert galaxies from the Palomar spectroscopic survey: the X-ray absorption distribution
• A Joint Mid-Infrared Spectroscopic and X-Ray Imaging Investigation of Liner Galaxies
• [O III]$\lambda 5007$ and X-ray Properties of a Complete Sample of Hard X-ray Selected AGNs in the Local Universe
• SHINING, A Survey of Far Infrared Lines in Nearby Galaxies. I: Survey Description, Observational Trends, and Line Diagnostics
• The INTEGRAL/IBIS AGN catalogue I: X-ray absorption properties versus optical classification
• Unveiling the nature of INTEGRAL objects through optical spectroscopy. VII. Identification of 20 Galactic and extragalactic hard X-ray sources
• Unobscured Type 2 AGNs
• The X-ray nebula around the Seyfert 2 galaxy NGC4388
• Are X-ray Emitting Coronae around Super Massive Black Holes Outflowing?
• Mid-Infrared Properties of the Swift Burst Alert Telescope Active Galactic Nuclei Sample of the Local Universe. I. Emission-Line Diagnostics
• Unveiling the nature of INTEGRAL objects through optical spectroscopy. VIII. Identification of 44 newly detected hard X-ray sources
• A search for changing-look AGN in the Grossan catalog
• Chandra Observations of a 1.9 kpc Separation Double X-ray Source in a Candidate Dual AGN Galaxy at z=0.16
• Chandra Observations of MRK 273: Unveiling the Central AGN and the Extended Hot Gas Halo
• The accretion ratios in Seyfert 2 galaxies with and without hidden broad-line regions
• NuSTAR Reveals Extreme Absorption in z < 0.5 Type 2 Quasars
• X-ray Properties of Intermediate-mass Black Holes in Active Galaxies. III. Spectral Energy Distribution and Possible Evidence for Intrinsically X-ray-weak AGNs
• An enshrouded AGN in the merging starburst system Arp~299 revealed by BeppoSAX
• Elusive AGN in the XMM-Newton bright serendipitous survey
• Weak Hard X-ray Emission from Two Broad Absorption Line Quasars Observed with NuSTAR: Compton-thick Absorption or Intrinsic X-ray Weakness?
• INTEGRAL/IBIS Extragalactic survey: 20-100 keV selected AGN
• Investigation of Dual Active Nuclei, Outflows, Shock-Heated Gas, and Young Star Clusters in Markarian 266
• Lifting the Veil on Obscured Accretion: Active Galactic Nuclei Number Counts and Survey Strategies for Imaging Hard X-ray Missions
• Unveiling the nature of INTEGRAL objects through optical spectroscopy. III. Observations of seven southern sources
• NuSTAR Observations of Heavily Obscured Quasars at z ~ 0.5
• The Near-Infrared Coronal Line Spectrum of 54 Nearby Active Galactic Nuclei
• NuSTAR Observations of the Compton-thick Active Galactic Nucleus and Ultraluminous X-ray Source Candidate in NGC 5643
• Fitting LINER nuclei within the AGN family: A matter of obscuration?
• XMM-Newton Observations of a Complete Sample of Optically Selected Type 2 Seyfert Galaxies
• The Multitude of Unresolved Continuum Sources at 1.6 microns in Hubble Space Telescope images of Seyfert Galaxies
• Indecent Exposure in Seyfert 2 Galaxies: A Close Look
• Modeling the Nuclear Infrared Spectral Energy Distribution of Type II Active Galactic Nuclei
• BASS XXIV: The BASS DR2 Spectroscopic Line Measurements and AGN Demographics
• X-ray Spectral Constraints for z~2 Massive Galaxies: The Identification of Reflection-Dominated Active Galactic Nuclei
• Parsec-Scale Images of Flat-Spectrum Radio Sources in Seyfert Galaxies
• Unveiling the nature of INTEGRAL objects through optical spectroscopy. X. A new multi-year, multi-observatory campaign
• Seyfert 2 Galaxies with Spectropolarimetric Observations
• On the nature of unabsorbed Seyfert 2 galaxies
• Fitting the spectrum of the X-ray background: the effects of high metallicity absorption
• The Unified Model of Active Galactic Nuclei: I. Non-hidden Broad Line Region Seyfert 2 and Narrow Line Seyfert 1 Galaxies
• Molecular Hydrogen Excitation around Active Galactic Nuclei
• Swift-XRT observation of 34 new INTEGRAL/IBIS AGNs: discovery of Compton thick and other peculiar sources
• NLS1 galaxies and estimation of their central black hole masses from the X-ray excess variance method
• Anatomy of the AGN in NGC 5548 VIII. XMM-Newton's EPIC detailed view of an unexpected variable multilayer absorber
• A wide search for obscured Active Galactic Nuclei using XMM-Newton and WISE
• X-ray emission from Seyfert 2 galaxies with optical polarized broad lines
• A Composite Seyfert 2 X-ray Spectrum: Implications for the Origin of the Cosmic X-ray Background
• A view of the narrow-line region in the infrared: active galactic nuclei with resolved fine-structure lines in the Spitzer archive
• Uncovering Obscured Active Galactic Nuclei in Homogeneously Selected Samples of Seyfert 2 Galaxies
• Chandra and XMM Observations of Type II Quasars from the SDSS
• Discovery of Water Maser Emission in Five AGN and a Possible Correlation Between Water Maser and Nuclear 2-10 keV Luminosities
• The merger-driven evolution of warm infrared luminous galaxies
• Searching for Compton-thick active galactic nuclei at z~0.1
• A Medium Survey of the Hard X-Ray Sky with ASCA. II.: The Source's Broad Band X-Ray Spectral Properties
• On the LINER nuclear obscuration, Compton-thickness and the existence of the dusty torus; Clues from Spitzer/IRS spectra
• X-ray spectral variability of Seyfert 2 galaxies
• Herschel Far-Infrared Photometry of the Swift Burst Alert Telescope Active Galactic Nuclei Sample of the Local Universe. I. PACS Observations
• Polycyclic Aromatic Hydrocarbons in Seyfert and star-forming galaxies
• Spectropolarimetry of a Complete Infrared Selected Sample of Seyfert 2 Galaxies
• SDSS-IV eBOSS Spectroscopy of X-ray and WISE AGN in Stripe 82X: Overview of the Demographics of X-ray and Mid-Infrared Selected Active Galactic Nuclei
• Unveiling the nature of INTEGRAL objects through optical spectroscopy. IV. A study of six new hard X-ray sources
• Compact Nuclear Starbursts in Seyfert 2 Galaxies from the CfA and 12 Micron Samples
• The Unified model and the Seyfert 2 infrared dichotomy
• Environmental dependence of AGN activity. I.: the effects of host galaxy
• Search for Molecular Outflows in Local Volume AGN with Herschel-PACS
• The HELLAS2XMM survey.VIII. Optical identifications of the extended sample
• New Compton-thick AGN in the circumnuclear water maser hosts UGC3 789 and NGC 6264
• The variable and non-variable X-ray absorbers in Compton-thin type-II Active Galactic Nuclei
• Unabsorbed Seyfert 2 galaxies: the case of "naked" AGN
• Characterising the Far-infrared Properties of Distant X-ray Detected AGNs: Evidence for Evolution in the Infrared--X-ray Luminosity Ratio
• Infrared spectroscopy around 4micron of Seyfert 2 galaxies: Obscured broad line regions and coronal lines
• The XMM large scale structure survey: optical vs. X-ray classifications of active galactic nuclei and the unified scheme
• The quest for Type 2 quasars: Chandra observations of luminous obscured quasars in the Sloan Digital Sky Survey
• Hydrocarbon Dust Absorption in Seyfert Galaxies and ULIRGs
• Scattered X-rays in Obscured Active Galactic Nuclei and their Implications for Geometrical Structure and Evolution
• Hard X-ray Variability of AGN
• X-ray Constraints on the AGN Properties in Spitzer-IRS identified z~2 Ultraluminous Infrared Galaxies
• H1320+551: A Seyfert 1.8/1.9 galaxy with an unabsorbed X-ray spectrum
• The Phoenix galaxy: UGC4203 re-birth from its ashes?
• The intrinsic emission of Seyfert galaxies observed with BeppoSAX/PDS I. Comparison of the average spectra of the three classes of Seyfert Galaxies
• Optical vs. infrared studies of dusty galaxies and AGN: (I) Nebular emission lines
• Unveiling the nature of INTEGRAL objects through optical spectroscopy. II. The nature of four unidentified sources
• X-Ray Spectral Variability of the Seyfert Galaxy NGC 4051 Observed with Suzaku
• A New Infrared Criterion for Selecting Active Galactic Nuclei to Lower Luminosities
• Star formation and AGN activity in a sample of local Luminous Infrared Galaxies through multi-wavelength characterization
• The weak neutral Fe fluorescence line and long-term X-ray evolution of the Compton-thick AGN in NGC 7674
• NICMOS Imaging of Molecular Hydrogen Emission in Seyfert Galaxies
• Herschel Far-Infrared Photometry of the Swift Burst Alert Telescope Active Galactic Nuclei Sample of the Local Universe. II. SPIRE Observations
• Multi-phase outflows in post starburst E+A galaxies -- II. A direct connection between the neutral and ionized outflow phases
• Delving Into X-ray Obscuration of Type 2 AGN, Near and Far
• Optical and Near-Infrared Spectroscopy of a High-Redshift, Hard X-ray Emitting Spiral Galaxy
• An Archival Chandra and XMM-Newton Survey of Type 2 Quasars
• A Chandra view of NGC 3621: a bulgeless galaxy hosting an AGN in its early phase?
• The AGN nature of 11 out of 12 Swift/RXTE unidentified sources through optical and X-ray spectroscopy
• Restarting activity in the nucleus of PBC J2333.9-2343: an extreme case of jet realignment
• Evidence for Rapidly Rotating Black Holes in FR I Radio Galaxies
• X-ray spectral properties of Seyfert galaxies and the unification scheme
• The OPTX Project IV: How Reliable is [OIII] as a Measure of AGN Activity?
• A New Sample of Buried Active Galactic Nuclei Selected from the Second XMM-Newton Serendipitous Source Catalogue
• The infrared luminosity of the torus and the visibility of scattered broad line emission in Seyfert 2 galaxies
• Optical Properties of Host Galaxies of Extragalactic Nuclear Water Masers
• Optical and mid-infrared line emission in nearby Seyfert galaxies
• Disclosing the properties of low-redshift dual AGN through XMM-Newton and SDSS spectroscopy
• The remarkable X-ray spectrum of the Broad-Line Radio Galaxy 3C 445
• XMM-Newton observations of ULIRGs I: A Compton-thick AGN in IRAS19254-7245
• Soft X-ray properties of a spectroscopically selected sample of interacting and isolated Seyfert galaxies
• A deep INTEGRAL hard X-ray survey of the 3C 273/Coma region
• The XMM-Newton view of NGC 6251
• A Radio Polarimetric Study to Disentangle AGN Activity and Star-Formation in Seyfert Galaxies
• A deep Chandra look at the low L_B elliptical NGC821: X-ray binaries, a galactic wind and emission at the nucleus
• A deep Chandra, VLA and Spitzer IRAC study of the very low luminosity nucleus of the elliptical NGC821
• On the nuclear obscuration of H2O maser galaxies
• An X-ray view of absorbed INTEGRAL AGN
• The Difference in Narrow Fe KαLine Emission Between Seyfert 1 and Seyfert 2 Galaxies
• Unveiling the AGN powering the "Composite" Seyfert/Star-forming galaxy NGC 7679: BeppoSAX and ASCA results
• An X-ray and Near-IR spectroscopic analysis of the ULIRG IRAS 05189-2524
• New water masers in Seyfert and FIR bright galaxies. IV. Interferometric follow-ups
• The column density distribution of hard X-ray radio galaxies
• On the nature of X-ray absorption in Seyfert 2 galaxies
• About AGN ionization echoes, thermal echoes, and ionization deficits in low redshift Lyman-alpha blobs
• X-ray versus Optical Observations of Active Galactic Nuclei: Evidence for Large Grains?
• Nuclear obscuration and scattering in Seyfert 2 galaxies
• The Different Nature in Seyfert 2 Galaxies With and Without Hidden Broad-Line Regions
• X-ray Emission from Megamaser Galaxy IC 2560
• X-ray absorption in distant type II QSOs
• The nature of the torus in the heavily obscured AGN Markarian 3: an X-ray study
• A Chandra observation of the z=2.285 galaxy FSC10214+4724: Evidence for a Compton-thick quasar?
• The nature of fifty Palermo Swift-BAT hard X-ray objects through optical spectroscopy
• A new sample of X-ray selected narrow emission-line galaxies. I. The nature of optically elusive AGN
• The BeppoSAX view of the X-ray active nucleus of NGC4258
• Accurate classification of 29 objects detected in the 39 months Palermo Swift/BAT hard X-ray catalogue
• Unveiling the nature of INTEGRAL objects through optical spectroscopy. IX. 22 more identifications, and a glance into the far hard X-ray Universe
• X-ray colour-colour selection for heavily absorbed AGN
• High Energy spectra of Seyferts and Unification schemes
• Suppressed star formation in circumnuclear regions in Seyfert galaxies
• Active Galactic Nucleus Pairs from the Sloan Digital Sky Survey. III. Chandra X-ray Observations Unveil Obscured Double Nuclei
• Chandra observations of NGC4698: a Seyfert-2 with no absorption
• The Chandra Deep Field-North Survey. XVI. The X-ray properties of moderate-luminosity Active Galaxies at z>4
• An Off-Nucleus Nonstellar Black Hole in the Seyfert Galaxy NGC 5252
• Complex Absorption Hides a Type II QSO in IRAS 13197-1627
• Measuring the level of nuclear activity in Seyfert galaxies and the unification scheme
• A comparison between the soft X-ray and [O III] morphologies of active galactic nuclei
• The X-ray view of optically selected dual AGN
• Stellar and gaseous velocity dispersions in type II AGNs at 0.3<z<0.83 from the Sloan Digital Sky Survey
• Where are Compton-thick radio galaxies? A hard X-ray view of three candidates
• The nature of Composite Seyfert/Star-forming galaxies revealed by X-ray observations
• Adaptive optics near-IR imaging of NGC2992 - unveiling core structures related to radio figure-8 loops
• A search for broad infrared recombination lines in NGC 1068
• IGR J16351-5806: another close by Compton-thick AGN
• An RXTE Observation of NGC 6300: a new bright Compton reflection Dominated Seyfert 2 Galaxy
• Constraining the X-ray reflection in low accretion rate AGN using XMM-Newton, NuSTAR and Swift
• The infrared to X-ray correlation spectra of unobscured type 1 active galactic nuclei
• Evidence for X-ray Obscuration in Type II Quasar Candidates from the Sloan Digital Sky Survey
• Suzaku observation of the LINER NGC 4102
• On the relation between the coronal line emission and the IR/X-ray emission in Seyfert galaxies
• The Second Nucleus of NGC 7727: Direct Evidence for the Formation and Evolution of an Ultracompact Dwarf Galaxy
• The Hunt for Red Quasars: Luminous Obscured Black Hole Growth Unveiled in the Stripe 82 X-ray Survey
• Investigating the nuclear activity of barred spiral galaxies: the case of NGC 1672
• Chandra X-ray and Hubble Space Telescope Imaging of Optically Selected Kiloparsec-Scale Binary Active Galactic Nuclei II: Host Galaxy Morphology and AGN Activity
• Simultaneous X-Ray and optical spectroscopy of the Seyfert galaxy Mrk 993
• Accretion disk versus jet orientation in H${}_2$O megamaser galaxies
• 4C 39.29 - extended emission around a powerful Type 2 quasar
• X-ray observations of the Compton-thick Seyfert 2 galaxy, NGC 5643
• The X-ray variability of Seyfert 1.8/1.9 galaxies
• Suzaku and SWIFT-BAT observations of a newly discovered Compton-thick AGN
• Constraining black hole masses in low-accreting AGN using X-ray spectra
• Absence of nuclear polycyclic aromatic hydrocarbon emission from a compact starburst: The case of the type-2 quasar Mrk 477
• The Spectral Energy Distributions of Red 2MASS AGN
• Low-Mass Active Galactic Nuclei with Rapid X-Ray Variability
• The 1 keV to 200 keV X-ray Spectrum of NGC 2992 and NGC 3081
• The high-ionization IR fine-structure lines as bolometric indicators of the AGN power: study of the complete 12 micron AGN sample
• Nuclear Infrared Spectral Energy Distribution of Type II Active Galactic Nuclei
• The starburst-AGN connection in the merger galaxy Mrk 938: an infrared and X-ray view
• A new sample of X-ray selected narrow emission-line galaxies. II. Looking for True Seyfert 2
• The off-centered Seyfert-like compact emission in the nuclear region of NGC 3621
• X-ray spectroscopy of the Compton-thick Seyfert 2 ESO 138-G1
• The X-ray luminous galaxies optically classified as star forming are mostly narrow line Seyfert 1s
• Reflection-dominated nuclear X-ray emission in the early-type galaxy ESO 565--G019
• A Tale of Two Narrow-Line Regions: Ionization, Kinematics, and Spectral Energy Distributions for a Local Pair of Merging Obscured Active Galaxies
• Formation of Obscuring Walls by Radiation Force from Circumnuclear Starbursts and Implications for Starburst-Active Galactic Nucleus Connection
• The nature of the absorbing torus in compact Radio Galaxies
• Discovery of Compton-thick quasars in the Sloan Digital Sky Survey
• Galaxy and Mass Assembly (GAMA): A $\text{WISE}$ study of the activity of emission-line systems in G23
• Observational hints on the torus obscuring gas behaviour through X-rays with NuSTAR data
• Nuclear obscuration in the high-ionization Seyfert 2 galaxy Tol 0109-383
• X-ray observations of the Ultraluminous infrared galaxy IRAS19254-7245 (The Superantennae)
• Obscuration of Active Galactic Nuclei by Circumnuclear Starbursts
• The Effect of Partial Obscuration on the Luminosity Dependence of the Obscured Fraction in Active Galactic Nuclei
• An Accreting, Anomalously Low Mass Black Hole at the Center of Low Mass Galaxy IC 750
• Are SMBHs shrouded by "super-Oort" clouds of comets and asteroids?
• Investigating the central engine of Seyfert 2 galaxies with and without Polarized Broad Lines
• The XMM-Newton spectrum of the high-z optically-obscured QSO RX J1343.4+0001: a classic radio quiet QSO
• The energy budget for X-ray to infrared reprocessing in Compton-thin and Compton-thick active galaxies
• The properties of the X-ray corona in the distant ($z=3.91$) quasar APM 08279+5255
• The relation between the mid-infrared emission and Black Hole Mass in Active Galactic Nuclei: A direct way to probe black hole growth?
• A More Efficient Search for H2O Megamaser Galaxies : The Power of the X-ray and Mid-infrared Photometry
• Characterisation of a candidate dual AGN
• X-ray observations of the'composite' Seyfert/star-forming galaxy IRAS00317-2142
• Nuclear X-ray properties of the peculiar radio-loud hidden AGN 4C+29.30
• The CaT strength in Seyfert nuclei revisited: analyzing young stars and non-stellar light contributions to the spectra
• AGN in the CALIFA survey: X-ray detection of nuclear sources
• Hidden Broad-line Regions in Seyfert 2 Galaxies: from the spectropolarimetric perspective
• Megamaser detection and nuclear obscuration in Seyfert galaxies
• A unique X-ray unabsorbed Seyfert 2 galaxy IRAS F01475-0740
• Soft gamma-ray selected giant radio galaxies: an update
• X-ray Spectroscopy and Variability of AGN Detected in the 2 Ms Chandra Deep Field-North Survey
• An XMM-Newton study of active-inactive galaxy pairs
• Deep X-ray spectroscopy and imaging of the Seyfert 2 galaxy, ESO 138-G001
• Suzaku X-ray spectral study of the Compton-thick Seyfert galaxy NGC 5135
• XMM Observations of the Seyfert 2 Galaxy NGC 7590: the Nature of X-ray Absorption
• XMM-Newton spectra of hard spectrum Rosat AGN: X-ray absorption and optical reddening
• The NuSTAR view of the true Type 2 Seyfert NGC3147
• XMM-Newton reveals a Seyfert-like X-ray spectrum in the z=3.6 QSO B1422+231
• BeppoSAX/PDS serendipitous detections at high galactic latitudes
• The study of Seyfert 2 galaxies with and without infrared broad lines
• The first optical validation of an XLEO: a detection in the XMM-Newton observation of the CDFS
• Are Seyfert 2 Galaxies without Polarized Broad Emission Lines More Obscured?
• ISO observations of four active galaxies
• The XMM spectral catalog of SDSS optically selected Seyfert 2 galaxies
• The Compton-thick quasar at the heart of the high-redshift giant radio galaxy 6C 0905+39
• The AGN Source Population in the Chandra Deep Field-North Survey: Constraints from X-ray Spectroscopy and Variability
• Optical spectroscopic classification of 35 hard X-ray sources from the Swift-BAT 70-month catalogue
• Embedded AGN and star formation in the central 80 pc of IC 3639
• X-ray long-term variations in the low-luminosity AGN NGC835 and its circumnuclear emission
• Properties of IR selected Active Galactic Nuclei
• SDSS-IV MaNGA: Identification and Multiwavelength Properties of Type-1 AGN in the DR15 sample
• The Complex X-ray Obscuration Environment in the Radio Loud Type 2 Quasar 3C 223
• Double-nucleus elliptical MCG-01-12-005 in an X-ray emitting cluster of galaxies
• The luminous infrared composite Seyfert 2 galaxy NGC 7679 through the [O III] 5007 emission line
• X-ray view of four high-luminosity Swift/BAT AGN: Unveiling obscuration and reflection with Suzaku
• On the origin of X-ray oxygen emission-lines in obscured AGN
• IC 485:a new candidate disk-maser galaxy at $\sim$100 Mpc distance. Milliarcsecond resolution study of the galaxy nucleus and of the $H_{2}O$ megamaser
• The X-ray Nature of Nucleus in Seyfert 2 Galaxy NGC 7590
• Mkn 463 field observed by BeppoSAX
• Obscured Narrow-Line Seyfert 1 Galaxy Candidate Mrk 1388 with Nonthermal Jets
• A search for H${}_2$O masers in 100 active dwarf galaxies
• The extragalactic nature of the serendipitous BeppoSAX source 2MASX J14585116-1652223
• The XMM-Newton hard band wide angle Survey
• Multi-wavelength properties of the high-energy bright Seyfert 1 galaxy IGR J18027-1455