Issue |
A&A
Volume 388, Number 3, June IV 2002
|
|
---|---|---|
Page(s) | 787 - 792 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361:20020471 | |
Published online | 10 June 2002 |
The Phoenix galaxy: UGC 4203 re-birth from its ashes?
1
XMM-Newton Science Operation Center, VILSPA, ESA, Apartado 50727, 28080 Madrid, Spain
2
Dipartimento di Fisica, Università degli Studi Roma Tre Via della Vasca Navale 84, 00146 Roma, Italy
3
Osservatorio Astronomico di Roma, Via dell'Osservatorio, 00144 Monteporzio Catone, Italy
Corresponding author: M. Guainazzi, mguainaz@xmm.vilspa.esa.es
Received:
3
September
2001
Accepted:
26
March
2002
We report on a dramatic transition between a Compton-thick, reflection-dominated state and a Compton-thin state in the Seyfert 2 galaxy UGC 4203, 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.
Key words: X-rays: galaxies / galaxies: active / galaxies: Seyfert / galaxies: individual: UGC 4203 / galaxies: nuclei
© ESO, 2002
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.