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Studying the long-time variability of the Seyfert 2 galaxy NGC 4388 with INTEGRAL and Swift

Fedorova, E. V. ; Beckmann, V. ; Neronov, A. ; Soldi, S.

In: Monthly Notices of the Royal Astronomical Society, 2011, vol. 417, no. 2, p. 1140-1147

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    Title
    • Studying the long-time variability of the Seyfert 2 galaxy NGC 4388 with INTEGRAL and Swift
    Author
    • Fedorova, E. V.. Astronomical Observatory of the Kiev Tarass Schevchenko University, Kiev 03040, Ukraine
    • Beckmann, V.. François Arago Centre, APC, Université Paris Diderot, CNRS/IN2P3, CEA/DSM, Obs. Paris, 13 rue Watt, 75205 Paris Cedex 13, France
    • Neronov, A.. ISDC Data Centre for Astrophysics, Chemin d'Écogia 16, 1290 Versoix, Switzerland
    • Soldi, S.. Laboratoire AIM - CNRS - CEA/DSM - Université Paris Diderot (UMR 7158), CEA Saclay, DSM/IRFU/SAp, 91191 Gif-sur-Yvette, France
    Document Type
    • Postprint
    OAI-PMH Identifier
    • oai:doc.rero.ch:298319
    Summary
    We present analysis results on the Seyfert 2 galaxy NGC 4388 based on 6 yr of INTEGRAL data combined with Swift/Burst Alert Telescope survey and Swift/X-Ray Telescope pointed observations. These data, taken from 2003 to 2009, allow us to study the broad-band properties of this active galactic nucleus in the 0.3-300 keV energy range. The continuum emission of NGC 4388 is well represented by an absorbed power-law model with exponential cut-off at high energies and an upper limit on the reflection component of R < 0.5. We find slow strong variations of the hard X-ray emission, indicating both flux and spectral slope changes on the 3-6 months time-scale. In comparison with previous results on NGC 4388, the source shows a complex variability behaviour, i.e. the spectral shape and the 20-60 keV flux vary independently