1WGA J2223.7-0206: A Narrow-Line Quasi-Stellar Object in the XMM-Newton field of view of 3C 445 ^*

Istituto di Astrofisica Spaziale e Fisica Cosmica (IASF) del CNR, Sezione di Bologna, via Gobetti 101, 40129 Bologna, Italy

Corresponding author: P. Grandi, grandi@bo.iasf.cnr.it

Received: 21 November 2003
Accepted: 30 January 2004

Abstract

We report the discovery of a Narrow Line QSO located at about  from the Broad Line Radio Galaxy 3C 445. The source, 1WGA J2223.7-0206, although already revealed by ROSAT, has never been optically identified previously. An XMM-Newton observation of 3C 445 has allowed, for the first time, an accurate X-ray spectral study of 1WGA J2223.7-0206, revealing an ultra-soft spectrum and fast flux variations typical of Narrow Line AGN. The 0.2–10 keV spectrum is well represented by a power law () plus a black body component ( eV) absorbed by Galactic . About  of the X-ray flux (  10^-13 erg cm^-2 s^-1) is emitted below 2 keV. The  keV flux is observed to decrease by about a factor 1.6 in about 5000 s. 
The optical observations, triggered by the X-ray study, confirm the Narrow Line AGN nature of this source. The continuum is blue with typical AGN emission lines, pointing to a redshift . The full width half maximum of H_β and the flux ratio [O iii]/H_β are 2000 km s^-1 and 0.21, respectively. The optical luminosity (M_R=-23.2) and the point-like appearance in the optical images identify 1WGA J2223.7-0206  as a Narrow Line QSO. 
From the optical-UV-X-ray Spectral Energy Distribution we obtain a lower limit of the bolometric luminosity of 1WGA J2223.7-0206 (  10⁴⁵ erg s^-1) implying, for accretion rates close to the Eddington limit, a black hole mass   .