A long observation of NGC 5548 by BeppoSAX: The high-energy cutoff, intrinsic spectral variability, and a truly warm absorber

Authors
Nicastro, F Piro, L De Rosa, A Feroci, M Grandi, P Fiore, F Elvis, M Haardt, F Kaastra, J Malizia, A Maraschi, L Matt, G Perola, GC Petrucci, PO
Citation
F. Nicastro et al., A long observation of NGC 5548 by BeppoSAX: The high-energy cutoff, intrinsic spectral variability, and a truly warm absorber, ASTROPHYS J, 536(2), 2000, pp. 718-728
Citations number
39
Categorie Soggetti
Space Sciences
Journal title
ASTROPHYSICAL JOURNAL
ISSN journal
0004637X → ACNP
Volume
536
Issue
2
Year of publication
2000
Part
1
Pages
718 - 728
Database
ISI
SICI code
0004-637X(20000620)536:2<718:ALOON5>2.0.ZU;2-A
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 an d O VIII absorption K edges and a possible blended O VII-O VIII K alpha,bet a emission feature at 0.54(-0.06)(+0.07) keV, inconsistent with a purely ph otoionized gas in equilibrium. We propose that the temperature of the absor bing and emitting gas is similar to 10(6) K so that both collisional ioniza tion and photoionization contribute.