A Long Observation of NGC 5548 by BeppoSAX: the High Energy Cut-off, Intrinsic Spectral Variability and a Truly Warm Absorber

Abstract

NGC 5548 was observed by BeppoSAX in a single long (8 day) observation from 0.2 to 200 keV. We find (1) the spectral variation of the source is produced by a change of the intrinsic power law slope; (2) a high energy cut-off at $E_c=115_{-27}^{+39}$ keV with a hint of change of $E_c$ with flux; (3) OVII and OVIII absorption K edges, and a possible blended OVII-OVIII K$\alpha ,\beta$ emission feature at $0.54_{-0.06}^{+0.07}$ keV, inconsistent with a purely photoionized gas in equilibrium. We propose that the temperature of the absorbing and emitting gas is $\sim 10^6$ K so that both collisional ionization and photoionization contribute.

23 pages, 8 figures. Accepted for publication in The Astrophysical Journal

References in corpus (4)

• Central Masses and Broad-Line Region Sizes of Active Galactic Nuclei: I. Comparing the Photoionization and Reverberation Techniques
• Resonant Absorption in the AGN spectra emerging from photoionized gas: differences between steep and flat ionizing continua
• Intrinsic Absorption Lines in the Seyfert 1 Galaxy NGC 5548: UV Echelle Spectra from the Space Telescope Imaging Spectrograph
• Multiple Velocity Components in the CIV Absorption Line of NGC5548

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