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 Ec= 115+39-27 keV with a hint of change of Ec with flux; (3) OVII and OVIII absorption K edges, and a possible blended OVII-OVIII Kα,β emission feature at 0.54+0.07-0.06 keV, inconsistent with a purely photoionized gas in equilibrium. We propose that the temperature of the absorbing and emitting gas is 106 K so that both collisional ionization and photoionization contribute.
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