Open AccessH1320+551: a type 1.8/1.9 Seyfert galaxy with an unabsorbed X‐ray spectrum
Author(s) -
Barcons X.,
Carrera F. J.,
Ceballos M. T.
Publication year - 2003
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2003.06238.x
Subject(s) - physics , balmer series , astrophysics , galaxy , equivalent width , active galactic nucleus , black body radiation , emission spectrum , line (geometry) , rest frame , astronomy , spectral line , optics , geometry , mathematics , redshift , radiation
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 Fe K 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.