A multi-epoch X-ray study of the nearby Seyfert 2 galaxy NGC 7479: Linking column density variability to the torus geometry

Abstract

Active galactic nuclei (AGN) are powered by accreting supermassive black holes, surrounded by a torus of obscuring material. Recent studies have shown how the torus structure, formerly thought to be homogeneous, appears to be 'patchy': the detection of variability in the line-of-sight hydrogen column density, in fact, matches the description of an obscurer with a complex structure made of clouds with different column density. In this work, we perform a multi-epoch analysis of the X-ray spectra of the Seyfert 2 galaxy NGC 7479 in order to estimate its torus properties, such as the average column density and the covering factor. The measurement of the line-of-sight hydrogen column density variability of the torus allows us to obtain an upper limit on the cloud distance from the central engine. In addition, using the X-ray luminosity of the source, we estimate the Eddington ratio to be in a range of Edd=0.04-0.05 over all epochs.

arXiv commentRe-submitted to ApJ after minor reviews

References in corpus (38)

• Unified Schemes for Radio-Loud Active Galactic Nuclei
• The Leiden/Argentine/Bonn (LAB) Survey of Galactic HI: Final data release of the combined LDS and IAR surveys with improved stray-radiation corrections
• The slope of the black-hole mass versus velocity dispersion correlation
• Collisional Plasma Models with APEC/APED: Emission Line Diagnostics of Hydrogen-like and Helium-like Ions
• AGN Dusty Tori: II. Observational Implications of Clumpiness
• An X-ray Spectral Model for Compton-Thick Toroidal Reprocessors
• The 1% Concordance Hubble Constant
• Bolometric luminosities and Eddington ratios of X-ray selected Active Galactic Nuclei in the XMM-COSMOS survey
• 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
• Extreme X-ray spectral variability in the Seyfert 2 Galaxy NGC 1365
• The luminosity dependence of the Type 1 AGN fraction
• First X-ray-Based Statistical Tests for Clumpy-Torus Models: Eclipse Events from 230 Years of Monitoring of Seyfert AGN
• New Spectral Model for Constraining Torus Covering Factors from Broadband X-ray Spectra of Active Galactic Nuclei
• ALMA observations of molecular tori around massive black holes
• The Nature of the Compton-thick X-ray Reprocessor in NGC 4945
• An Unveiling Event in the Type 2 AGN NGC4388: A Challenge for a Parsec Scale Absorber
• ALMA reveals the feeding of the Seyfert 1 nucleus in NGC 1566
• The power output of local obscured and unobscured AGN: crossing the absorption barrier with Swift/BAT and IRAS
• Redefining the torus: A unifying view of AGN in the infrared and sub-mm
• X-Ray Spectral Model from Clumpy Torus and Its Application to Circinus Galaxy
• X-ray spectral and eclipsing model of the clumpy obscurer in active galactic nuclei
• A search for changing-look AGN in the Grossan catalog
• ALMA captures feeding and feedback from the active galactic nucleus in NGC613
• NuSTAR Survey of Obscured Swift/BAT-selected Active Galactic Nuclei: II. Median High-energy Cutoff in Seyfert II Hard X-ray Spectra
• The size of the X-ray emitting region in SWIFT J2127.4+5654 via a broad line region cloud X-ray eclipse
• The properties of the AGN torus as revealed from a set of unbiased NuSTAR observations
• C-GOALS II. Chandra Observations of the Lower Luminosity Sample of Nearby Luminous Infrared Galaxies in GOALS
• The variable and non-variable X-ray absorbers in Compton-thin type-II Active Galactic Nuclei
• Compton-thick AGN in the NuSTAR era III: A systematic study of the torus covering factor
• A Compton-thin Solution for the Suzaku X-ray Spectrum of the Seyfert 2 Galaxy Mkn 3
• NuSTAR Observations of 52 Compton-thick Active Galactic Nuclei Selected by the Swift/BAT All-sky Hard X-Ray Survey
• Physically motivated X-ray obscurer models
• Probing general relativistic effects during AGN X-ray eclipses
• On the association of ULXs with young superclusters: M82 X-1 and a new candidate in NGC 7479
• Inferring the morphology of AGN torus using X-ray spectra: A reliability study
• Properties of the Obscuring Torus in NGC 1052 from Multi-epoch Broadband X-ray Spectroscopy
• Star Formation Properties in Barred Galaxies(SFB). I. Ultraviolet-to-Infrared Imaging and Spectroscopic Studies of NGC 7479

Cited by in corpus (8)

• Neutrino signal from a population of Seyfert galaxies
• Hydrogen Column Density Variability in a Sample of Local Compton-Thin AGN
• Compton-thick AGN in the NuSTAR Era. IX. A Joint NuSTAR and XMM-Newton Analysis of Four Local AGN
• Compton-thick AGN in the NuSTAR Era X: Analysing seven local CT-AGN candidates
• The NuSTAR view of the changing look AGN ESO 323-G77
• A Multi-Wavelength Characterization of the Obscuring Medium at the Center of NGC 6300
• Chandra Follow-up Observations of Swift-BAT-selected AGNs III
• X-ray Spectral Variability as Probe of Multimessenger Emission in Blazar 5BZB J0630-24064