NGC 5548 was observed by BeppoSAX in a single long (8 day) observation from 0.2 to 200 keV. We find (1) spectral variation of the source produced by a change of the intrinsic power-law slope; (2) a high-energy cutoff at E-c = 115(-27)(+39) keV with a hint of change of E-c with flux; and (3) O VII and O VIII absorption K edges and a possible blended O VII-O VIII 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 similar to 10(6) K so that both collisional ionization and photoionization contribute.
Nicastro, F., Piro, L., De Rosa, A., Feroci, M., Grandi, P., Fiore, F., et al. (2000). A long observation of NGC 5548 by BeppoSAX: The high-energy cutoff, intrinsic spectral variability, and a truly warm absorber. THE ASTROPHYSICAL JOURNAL, 536(2), 718-728 [10.1086/308950].
A long observation of NGC 5548 by BeppoSAX: The high-energy cutoff, intrinsic spectral variability, and a truly warm absorber
MATT, Giorgio;
2000-01-01
Abstract
NGC 5548 was observed by BeppoSAX in a single long (8 day) observation from 0.2 to 200 keV. We find (1) spectral variation of the source produced by a change of the intrinsic power-law slope; (2) a high-energy cutoff at E-c = 115(-27)(+39) keV with a hint of change of E-c with flux; and (3) O VII and O VIII absorption K edges and a possible blended O VII-O VIII 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 similar to 10(6) K so that both collisional ionization and photoionization contribute.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
