The Phoenix galaxy: UGC 4203 re-birth from its ashes?

被引:40
作者
Guainazzi, M
Matt, G
Fiore, F
Perola, GC
机构
[1] ESA, VILSPA, XMM Newton Sci Operat Ctr, Madrid 28080, Spain
[2] Univ Studi Roma Tre, Dipartimento Fis, I-00146 Rome, Italy
[3] Osserv Astron Roma, I-00144 Monte Porzio Catone, Italy
来源
ASTRONOMY & ASTROPHYSICS | 2002年 / 388卷 / 03期
关键词
X-rays : galaxies; galaxies : active; galaxies : Seyfert; galaxies : individual : UGC 4203; galaxies : nuclei;
D O I
10.1051/0004-6361:20020471
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
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.
引用
收藏
页码:787 / 792
页数:6
相关论文
共 39 条
[1]   UNIFIED MODELS FOR ACTIVE GALACTIC NUCLEI AND QUASARS [J].
ANTONUCCI, R .
ANNUAL REVIEW OF ASTRONOMY AND ASTROPHYSICS, 1993, 31 :473-521
[2]   SPECTROPOLARIMETRY AND THE NATURE OF NGC-1068 [J].
ANTONUCCI, RRJ ;
MILLER, JS .
ASTROPHYSICAL JOURNAL, 1985, 297 (02) :621-632
[3]  
ANTONUCCI RRJ, 1990, APJ, V367, pL17
[4]   X-ray emission from Seyfert 2 galaxies with optical polarized broad lines [J].
Awaki, H ;
Ueno, S ;
Taniguchi, Y ;
Weaver, KA .
ASTROPHYSICAL JOURNAL, 2000, 542 (01) :175-185
[5]  
AWAKI H, 1991, PUBL ASTRON SOC JPN, V43, P195
[6]   A three-dimensional diagnostic diagram for Seyfert 2 galaxies: Probing X-ray absorption and Compton thickness [J].
Bassani, L ;
Dadina, M ;
Maiolino, R ;
Salvati, M ;
Risaliti, G ;
Della Ceca, R ;
Matt, G ;
Zamorani, G .
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES, 1999, 121 (02) :473-482
[7]   The circumnuclear X-ray reflectors in NGC 1068 and the Circinus galaxy [J].
Bianchi, S ;
Matt, G ;
Iwasawa, K .
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 2001, 322 (03) :669-680
[8]   THE DISCOVERY OF 5 NEW H2O MEGAMASERS IN ACTIVE GALAXIES [J].
BRAATZ, JA ;
WILSON, AS ;
HENKEL, C .
ASTROPHYSICAL JOURNAL, 1994, 437 (02) :L99-L102
[9]  
Clavel J, 2000, ASTRON ASTROPHYS, V357, P839
[10]   H I IN THE GALAXY [J].
DICKEY, JM ;
LOCKMAN, FJ .
ANNUAL REVIEW OF ASTRONOMY AND ASTROPHYSICS, 1990, 28 :215-261