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Register a new userTesting Comptonization models using BeppoSAX observations of Seyfert 1 galaxies
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Authors
P.O. Petrucci
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We used high quality BeppoSAX data of 6 Seyfert galaxies to test realistic thermal Comptonization models. Our main effort was to adopt a Comptonization model taking into account the anisotropy of the soft photon field. The best fit parameter values of the temperature and optical depth of the corona and of the reflection normalization obtained fitting this class of models to the data are substantially different from those derived fitting the same data with the power law + cut--off model commonly used. The two models also provide different trends and correlation between the physical parameters, which has major consequences for the physical interpretation of the data
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We test accurate models of Comptonisation spectra over BeppoSAX observations of Seyfert galaxies focusing on the long look at NGC 5548. The hot plasma temperature derived with these models is significantly higher than that obtained fitting the same data with a power law plus high energy cut off model for the continuum. This is due to the fact that in anisotropic geometries Comptonisation spectra show intrinsic curvature which moves the fitted high energy cut-off to higher energies. We also show preliminary results of our analysis of a sample of 5 other Seyfert galaxies.
We report on BeppoSAX broad band (0.1-100 keV) observations of bright Seyfert 2 galaxies and discuss the results in the framework of the unified theory of AGNs. The data are used to probe Nh distribution in type 2 objects and to identify heavily absorbed (10^24 <= Nh <= 10^25 cm^-2) sources, which are particularly bright in hard X-rays. They also provide, for the first time, high energy spectral data on Seyfert 2s and tight constraints on the shape of their intrinsic power law continuum. These results confirm the basic expectations of the unified theory and indicate where the INTEGRAL mission can give a substantial contribution.
We present new results from a Chandra HETG observation of NGC 5548 and give a comparison of absorption and emission features found in other Seyfert 1 galaxies using Chandra grating observations. Deep soft X-ray edges are seen in Mkn 509 and NGC 3783, consistent with ASCA data. In NGC 5548 and NGC 4501 the edges are weak but consistent with the low column densities. We show that the detection of a narrow, probably non-disk, component of the iron line is very common. However, just as importantly, it is not detected in some cases. We show the effect of removing this narrow component from the ASCA Fe-K line profile in NGC 4151, revealing the underlying true shape of the relativistic Fe-K line component.
We report broad band (0.1-200 keV) X-ray observations, made by BeppoSAX, of a sample of bright Seyfert 2 galaxies: NGC7172, NGC2110, NGC4507, Mkn 3 and NGC7674. These spectra provide a better understanding of the effects of X-ray reprocessing by cold material in the source and allow to put tighter constraints on the various spectral parameters involved. In particular, the data are used to determine, with less ambiguities than in the past, the shape of the intrinsic continuum emission by means of the high energy data. Within the small sample both Compton thin and Compton thick sources are found according to the expectations of the unified theory.
After a rapid introduction about the models of comptonization, we present some simulations that underlines the expected capabilities of Simbol-X to constrain the presence of this process in objects like AGNs or XRB.
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