The Phoenix galaxy: UGC4203 re-birth from its ashes?

Abstract

We report on a dramatic transition between a Compton-thick, reflection-dominated state and a Compton-thin state in the Seyfert 2 galaxy UGC4203, discovered by comparing a recent (May 2001) XMM-Newton observation with ASCA observations performed about six years earlier. This transition can be explained either as a change in the column density of the absorber, maybe due to moving clouds in a clumpy torus, or as the revival of a transient active nucleus, which was in a phase of very low activity when observed by ASCA. If the latter explanation is correct, spectral transitions of this kind provide observational support to the idea that Compton-thick and Compton-thin regions coexist in the same source, the former likely to be identified with the "torus", the latter with dust lanes on much larger scales.

6 Latex pages, 5 figures, To appear in Astronomy & Astrophysics

References in corpus (3)

• The European Photon Imaging Camera on XMM-Newton: The MOS Cameras
• The formerly X-ray reflection-dominated Seyfert~2 galaxy NGC6300
• On the nature of X-ray absorption in Seyfert 2 galaxies

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