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Browsing by Author "Di Gesu, L."

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    A fast and long-lived outflow from the supermassive black hole in NGC 5548
    Kaastra, J. S.; Kriss, G. A.; Cappi, M.; Mehdipour, M.; Petrucci, P. O.; Steenbrugge, K. C.; Arav, Nahum; Behar, E.; Bianchi, S.; Boissay, R.; Branduardi-Raymont, G.; Chamberlain, C.; Costantini, E.; Ely, J. C.; Ebrero, J.; Di Gesu, L.; Harrison, F. A.; Kaspi, S.; Malzac, J.; De Marco, B.; Matt, G.; Nandra, K.; Paltani, S.; Person, R.; Peterson, B. M.; Pinto, C.; Ponti, G.; Nunez, F. P.; De Rosa, A.; Seta, H.; Ursini, F.; de Vries, C. P.; Walton, D. J.; Whewell, M. (Amer Assoc Advancement Science, 2014-07-04)
    Supermassive black holes in the nuclei of active galaxies expel large amounts of matter through powerful winds of ionized gas. The archetypal active galaxy NGC 5548 has been studied for decades, and high-resolution X-ray and UV observations have previously shown a persistent ionized outflow. An observing campaign in 2013 with six space observatories shows the nucleus to be obscured by a long-lasting, clumpy stream of ionized gas never seen before. It blocks 90% of the soft X-ray emission and causes simultaneous deep, broad UV absorption troughs. The outflow velocities of this gas are up to five times faster than those in the persistent outflow, and at a distance of only a few light days from the nucleus, it may likely originate from the accretion disk.
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    Simultaneous XMM-Newton and HST-COS observation of 1H0419-577 The absorbing and emitting ionized gas
    Di Gesu, L.; Arav, Nahum; Borguet, B.; Detmers, R. G.; Ebrero, J.; Edmonds, Douglas; Kaastra, J. S.; Piconcelli, E.; Verbunt, F.; Constantini, E. (EDP Sciences, 2013-08)
    In this paper we analyze the X-ray, UV, and optical data of the Seyfert 1.5 galaxy 1H0419-577 with the aim of detecting and studying an ionized-gas outflow. The source was observed simultaneously in the X-rays with XMM-Newton and in the UV with HST-COS. Optical data were also acquired with the XMM-Newton Optical Monitor. We detected a thin, lowly ionized warm absorber (log xi approximate to 0.03, log N-H approximate to 19.9 cm(-2)) in the X-ray spectrum, which is consistent to be produced by the same outflow already detected in the UV. Provided the gas density estimated in the UV, the outflow is consistent to be located in the host galaxy at similar to kpc scale. Narrow emission lines were detected in the X-rays, in the UV and also in the optical spectrum. A single photoionized-gas model cannot account for all the narrow lines emission, indicating that the narrow line region is probably a stratified environment, differing in density and ionization. X-ray lines are unambiguously produced in a more highly ionized gas phase than the one emitting the UV lines. The analysis also suggests that the X-ray emitter may just be a deeper portion of the same gas layer producing the UV lines. Optical lines are probably produced in another disconnected gas system. The different ionization condition and the similar to pc scale location, suggested by the line width for the narrow lines emitters, are evidences against a connection between the warm absorber and the narrow line region in this source.