INTEGRAL observations of AGN in the Galactic Plane

Abstract

We present results on approximately one year of INTEGRAL observations of six AGN detected during the regular scans of the Galactic Plane. The sample is composed by five Seyfert 2 objects (MCG -05-23-16, NGC 4945, the Circinus galaxy, NGC 6300, ESO 103-G35) and the radio galaxy Centaurus A. The continuum emission of each of these sources is well represented by a highly absorbed (NH > 1e22 1/cm^2) power law, with average spectral index Gamma = 1.9 +/- 0.3. A high energy exponential cut-off at Ec ~ 50 keV is required to fit the spectrum of the Circinus galaxy, whereas a lower limit of 130 keV has been found for NGC 4945 and no cut-off has been detected for NGC 6300 in the energy range covered by these INTEGRAL data. The flux of Centaurus A was found to vary by a factor of ~ 2 in 10 months, showing a spectral change between the high and low state, which can be modelled equally well by a change in the absorption (NH from 17e22 to 33e22 1/cm^2) or by the presence of a cut-off at >~ 120 keV in the low state spectrum. A comparison with recently reprocessed BeppoSAX/PDS data shows a general agreement with INTEGRAL results. The high energy cut-off in the hard X-ray spectra appears to be a common but not universal characteristic of Seyfert 2 and to span a wide range of energies.

arXiv comment12 pages, 12 figures, accepted for publication in A&A

References in corpus (31)

• ISGRI: the INTEGRAL Soft Gamma-Ray Imager
• In-flight Performance of the High Energy X-ray Timing Experiment on the Rossi X-ray Timing Explorer
• The INTEGRAL Science Data Centre (ISDC)
• The BeppoSAX view of bright Compton-thin Seyfert 2 galaxies
• Observations of Seyferts by OSSE and parameters of their X-ray/gamma-ray sources
• INTEGRAL/SPI ground calibration
• IBIS/PICsIT in-flight performances
• The formerly X-ray reflection-dominated Seyfert~2 galaxy NGC6300
• Soft X-ray spectroscopy of Compton-thick Seyfert 2 galaxies with BeppoSAX
• The Spiros imaging software for the Integral SPI spectrometer
• Unveiling the nature of three INTEGRAL sources through optical spectroscopy
• Structure of the Circumnuclear Region of Seyfert 2 Galaxies Revealed by RXTE Hard X-ray Observations of NGC 4945
• BeppoSAX average spectra of Seyfert galaxies
• First results from the INTEGRAL Galactic plane scans
• Simultaneous Chandra and RXTE observations of the nearby bright Seyfert 2 galaxy NGC4945
• INTEGRAL and XMM-Newton Spectral Studies of NGC 4388
• Simultaneous observations of the quasar 3C 273 with INTEGRAL, XMM-Newton and RXTE
• The intrinsic emission of Seyfert galaxies observed with BeppoSAX/PDS I. Comparison of the average spectra of the three classes of Seyfert Galaxies
• In flight calibration of the ISGRI camera
• The broad-band X-ray spectrum of the blazar PKS B1830-211 by Chandra and INTEGRAL
• An XMM-Newton Observation of the Seyfert 2 Galaxy NGC 6300. I. The Nucleus
• INTEGRAL observations of the field of the BL Lacertae object S5~0716+714
• BeppoSAX Observations of Centaurus A: the Hard Continuum and the Iron Line Feature
• An RXTE Observation of NGC 6300: a new bright Compton reflection Dominated Seyfert 2 Galaxy
• RXTE and BeppoSAX Observations of MCG -5-23-16: Reflection From Distant Cold Material
• BeppoSAX Observations of the Maser Sy2 Galaxy: ESO103-G35
• Observation of Cen A by the Rossi X-ray Timing Explorer
• Broadband X-ray spectrum of GRS 1734-292, a luminous Seyfert 1 galaxy behind the Galactic Center
• Investigating the central engine of Seyfert 2 galaxies with and without Polarized Broad Lines
• RXTE monitoring of Centaurus A
• Ubiquitous column density variability in Seyfert 2 Galaxies

Cited by in corpus (25)

• The Space Density of Compton Thick AGN and the X-ray Background
• The dusty torus in the Circinus galaxy: a dense disk and the torus funnel
• The Infrared Nuclear Emission of Seyfert Galaxies on Parsec Scales: Testing the Clumpy Torus models
• Testing the Unification Model for AGN in the Infrared: are the obscuring tori of Type 1 and 2 Seyferts different?
• The Second INTEGRAL AGN Catalogue
• The spectral energy distribution of the central parsecs of the nearest AGN
• The First INTEGRAL AGN Catalog
• Isotropic Mid-Infrared Emission from the Central 100 pc of Active Galaxies
• INTEGRAL/IBIS Extragalactic survey: 20-100 keV selected AGN
• The Hard X-ray 20-40 keV AGN Luminosity Function
• The Hard X-ray Emission of Cen A
• The dusty heart of Circinus: I. Imaging the circumnuclear dust in N-band
• Hard X-ray Variability of AGN
• Suzaku Observations of the Circinus galaxy
• A Chandra and ALMA Study of X-ray-irradiated Gas in the Central ~100 pc of the Circinus Galaxy
• INTEGRAL observations of AGN obscured by the Galactic Plane
• The hard X-ray continuum of Cen A observed with INTEGRAL SPI
• Multi-Zone warm and cold clumpy absorbers in 3 Seyfert galaxies
• The efficient low-mass Seyfert MCG-05-23-016
• Rolling down from the 30 keV peak: modelling the hard X-ray and gamma-ray backgrounds
• X-Ray Spectral Parameters for a Sample of 95 Active Galactic Nuclei
• Q2237+0305 in X-rays: spectra and variability with XMM-Newton
• Modeling time delays in the X-ray spectrum of the Seyfert galaxy MCG-6-30-15
• INTEGRAL and XMM-Newton observations towards the unidentified MeV source GRO J1411-64
• INTEGRAL/XMM views on the MeV source GRO J1411-64