A swan song: the disappearance of the nucleus of NGC 4051 and the echo of its past glory

Authors
Guainazzi, M Nicastro, F Fiore, F Matt, G McHardy, I Orr, A Barr, P Fruscione, A Papadakis, I Parmar, AN Uttley, P Perola, GC Piro, L
Citation
M. Guainazzi et al., A swan song: the disappearance of the nucleus of NGC 4051 and the echo of its past glory, M NOT R AST, 301(1), 1998, pp. L1-L4
Citations number
39
Categorie Soggetti
Space Sciences
Journal title
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
ISSN journal
00358711 → ACNP
Volume
301
Issue
1
Year of publication
1998
Pages
L1 - L4
Database
ISI
SICI code
0035-8711(19981121)301:1<L1:ASSTDO>2.0.ZU;2-9
Abstract
On 1998 May 9-11,BeppoSAX observed the low-luminosity Seyfert 1 galaxy NGC 4051 in an ultra-dim X-ray state. The 2-10 keV flux (1.26 x 10-(12) erg cm( -2) s(-1)) was about 20 times fainter than its historical average value, an d remained steady along the whole observation (similar to 2.3 d). The obser ved flat spectrum (Gamma similar or equal to 0.8) and intense iron line (EW similar or equal to 600 eV) are best explained by assuming that the active nucleus has switched off, leaving only a residual reflection component vis ible.