H1320+551: a type 1.8/1.9 Seyfert galaxy with an unabsorbed X-ray spectrum
Abstract
We present new optical spectroscopic and XMM-Newton X-ray observations of the active galactic nucleus (AGN) H1320+551. The optical data (consistent with but of better quality than a previously published spectrum) show this source to be a type 1.8/1.9 Seyfert galaxy at z= 0.0653. The narrow-line region is significantly reddened, with a Balmer decrement Hα/Hβ~ 6, and the broad-line region, with a barely detectable Hβ broad component, shows a much pronounced Balmer decrement (Hα/Hβ > 27). In spite of this, the EPIC pn X-ray spectrum exhibits a power-law continuum with a soft excess that is well fitted by a blackbody, with no photoelectric absorption above the Galactic value. An FeK emission line is also seen at a rest-frame energy ~6.5 keV with an equivalent width of ~400 eV, far too weak for the source to be Compton-thick. Reconciling the optical and X-ray data requires the narrow-line region to be internally reddened but with small covering factor over the nuclear emission, and the Balmer decrement of the broad-line region to be an intrinsic property rather than caused by reddening/absorption. The H1320+551 type 1.8/1.9 Seyfert galaxy is not consistent with being an obscured type 1 Seyfert nucleus, i.e. it does not match the basic AGN unified scheme hypothesis.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- March 2003
- DOI:
- 10.1046/j.1365-8711.2003.06238.x
- arXiv:
- arXiv:astro-ph/0211120
- Bibcode:
- 2003MNRAS.339..757B
- Keywords:
-
- galaxies: active;
- galaxies: Seyfert;
- X-rays: galaxies;
- Astrophysics
- E-Print:
- 9 pages, 9 eps figures, to appear in MNRAS