The BeppoSAX broad-band spectrum and variability of the Seyfert 1 NGC 3783
Abstract
BeppoSAX observed the Seyfert 1 galaxy NGC 3783 for ~ 5 days from 1998 June 6 to 1998 June 10. The average flux during the observation was F2-10 keV ~ 6x 10-11 ;erg cm-2 s-1. The long exposure provided a very high quality spectrum that exhibits all the typical features of Seyfert 1s. The high energy cut-off of the intrinsic continuum, at Ec=340 +/- m560107 keV, was detected for the first time in this object. During the observation the source showed modest flux variations ( ~ 20% in 2-10 keV) and spectral variability that can be completely explained by a change of the intrinsic slope Delta Gamma ~ 0.1. NGC 3783 is one of the few Seyfert 1s that exhibits a soft emission component in the BeppoSAX spectrum. This soft excess is well reproduced by a black body component with temperature kT ~ 0.2 keV. A warm absorber is also required to fit the soft X-ray spectrum. Both reprocessing features, the Compton reflection hump and the Fe emission line, were detected in our observation. In addition to a narrow iron line (as observed by Chandra) a broad component with sigma =0.72 +/- m1.280.27 keV and EW=115 +/- m76 eV, is required to fit the line. The observed Compton hump and the Fe line are well reproduced with the ionized (log xi =2.73 +/- m0.040.05) disc reflection model of Ross & Fabian. In this case the soft excess observed below 2 keV can be accounted for by the disc emissivity and no additional soft X-rays component is required to fit the spectrum.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- June 2002
- DOI:
- 10.1051/0004-6361:20020444
- arXiv:
- arXiv:astro-ph/0203344
- Bibcode:
- 2002A&A...387..838D
- Keywords:
-
- galaxies: individual: NGC 3783;
- galaxies: Seyfert;
- X-rays: galaxies;
- Astrophysics
- E-Print:
- 13 pages, 14 figures, accepted for publication in A&