A BeppoSAX observation of the Broad Line Radio-Galaxy 3C 390.3 is reported. For the first time, both the K-alpha iron line and a strong reflection hump, produced by the illumination of the primary X-ray emission on cold matter, are detected in this source. The 0.1-100 keV continuum is modeled by an absorbed hard power law (Gamma similar to 1.8) reflected at high energies by material with a fairly large covering factor (Omega/2 pi similar or equal to 1). The iron line is centered at similar or equal to 6.4 keV (rest frame), is intrinsically narrow (sigma = 73+/-(207)(73) eV), and has an equivalent width of similar or equal to 140 eV. We discuss the results in the context of current models for AGNs and suggest that the primary X-ray power law continuum is probably produced by a hot inner flow, while the reprocessed radiation comes from an outer cold thin disk, and/or from a thick torus at even larger radii. Further observations with BeppoSAX could distinguish between the latter two cases. Beamed radiation associated to the radio jet is unlikely to contribute significantly to the X-ray emission. Finally an historical study of the column density NH, also reported here, shows that the absorption along the Line of sight changes in time. The N-H time variability, which is not correlated with that of the primary continuum, seems to imply variations of the geometry of the absorber rather than Variations in the ionization state of the gas.
Grandi, P., Guainazzi, M., Haardt, F., Maraschi, L., Massaro, E., Matt, G., et al. (1999). Reprocessing and variable cold absorption in the broad-line radio galaxy 3C 390.3. ASTRONOMY & ASTROPHYSICS, 343(1), 33-40.
Reprocessing and variable cold absorption in the broad-line radio galaxy 3C 390.3
MATT, Giorgio;
1999-01-01
Abstract
A BeppoSAX observation of the Broad Line Radio-Galaxy 3C 390.3 is reported. For the first time, both the K-alpha iron line and a strong reflection hump, produced by the illumination of the primary X-ray emission on cold matter, are detected in this source. The 0.1-100 keV continuum is modeled by an absorbed hard power law (Gamma similar to 1.8) reflected at high energies by material with a fairly large covering factor (Omega/2 pi similar or equal to 1). The iron line is centered at similar or equal to 6.4 keV (rest frame), is intrinsically narrow (sigma = 73+/-(207)(73) eV), and has an equivalent width of similar or equal to 140 eV. We discuss the results in the context of current models for AGNs and suggest that the primary X-ray power law continuum is probably produced by a hot inner flow, while the reprocessed radiation comes from an outer cold thin disk, and/or from a thick torus at even larger radii. Further observations with BeppoSAX could distinguish between the latter two cases. Beamed radiation associated to the radio jet is unlikely to contribute significantly to the X-ray emission. Finally an historical study of the column density NH, also reported here, shows that the absorption along the Line of sight changes in time. The N-H time variability, which is not correlated with that of the primary continuum, seems to imply variations of the geometry of the absorber rather than Variations in the ionization state of the gas.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
