Obscuring clouds playing hide-and-seek in the Active Nucleus H0557-385
| Autor: | Longinotti, A. L., Bianchi, S., Ballo, L., de la Calle, I., Guainazzi, M. |
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| Rok vydání: | 2008 |
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| Druh dokumentu: | Working Paper |
| DOI: | 10.1111/j.1745-3933.2008.00571.x |
| Popis: | This paper reports on two XMM-Newton observations of the Seyfert 1 Galaxy H0557-385 obtained in 2006, which show the source at an historical low flux state, more than a factor of 10 lower than a previous XMM-Newton look in 2002. The low flux spectrum presents a strong Fe Kalpha line associated to a Compton reflection continuum. An additional spectral line around 6.6 keV is required to fit Kalpha emission from Fe XXV. The spectral curvature below 6 keV implies obscuration by neutral gas with a column density of 8*10^{23}cm^{-2} partially covering the primary emission, which still contributes for a few percent of the soft X-ray emission. Absorption by ionised material on the line of sight is required to fit the deep trough below 1 keV. The comparison of the two spectral states shows that the flux transition is to be ascribed entirely to intervening line-of-sight clouds with high column density. Comment: 5 pages, accepted for publication on MNRAS Letters |
| Databáze: | arXiv |
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