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Session 31 - Quasars.
Oral session, Wednesday, January 07
International Ballroom East,

[31.02] An Empirical UV Fe Template as Derived From I Zwicky 1

M. Vestergaard (Cph. Univ\,and\,SAO), B. J. Wilkes (SAO)

We present an empirical iron (Fe) spectrum template with emission mainly from Ultra-Violet (UV) Fe\,II. The template is useful for modeling and correcting for the significant contamination of the UV emission lines by Fe emission in QSO and AGN spectra.

Due to the large number of electron levels in Fe atoms, hundreds of emission line transitions are distributed across most of the UV and optical spectral regions. The weak (Fe) lines, in particular, blend together with other weak lines to form a pseudo-continuum above the intrinsically emitted continuum, even in high S/N QSO spectra. This severely complicates the study of weak non-Fe features and the wings of strong resonance lines. The increasing availability of improved atomic data and the availability of HST UV data help us both to develop an applicable observational Fe emission template and to begin to understand the Fe spectrum in terms of theoretical models.

In this paper we describe the development of such a template, using a high quality HST UV spectrum (\lambda 1100-3100Åof I\,Zw\,1, as well as its application. How significantly the presence of the Fe emission affects the Broad Emission Line measurements is also addressed along with the applicability to QSOs in general. In particular, this work reveals that what has commonly been identified as CIII] emission may in most cases have a different origin.

Program listing for Wednesday