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A NEAR-INFRARED TEMPLATE DERIVED FROM I Zw 1 FOR THE Fe II EMISSION IN ACTIVE GALAXIES.
- Source :
-
Astrophysical Journal . 5/20/2012, Vol. 751 Issue 1, p1-1. 1p. - Publication Year :
- 2012
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Abstract
- In active galactic nucleus spectra, a series of Fe II multiplets form a pseudo-continuum that extends from the ultraviolet to the near-infrared (NIR). This emission is believed to originate in the broad-line region, and it has been known for a long time that pure photoionization fails to reproduce it in the most extreme cases, as does the collisional excitation alone. The most recent models by Sigut & Pradhan include details of the Fe II ion microphysics and cover a wide range in the ionization parameter log Uion = (– 3.0 → –1.3) and density log nH = (9.6 → 12.6). With the aid of such models and a spectral synthesis approach, we studied for the first time in detail the NIR emission of I Zw 1. The main goals were to confirm the role played by Lyα fluorescence mechanisms in the production of the Fe II spectrum and to construct the first semi-empirical NIR Fe II template that best represents this emission, consequently allowing its clean subtraction in other sources. A good overall match between the observed Fe II+Mg II features with those predicted by the best-fitted model was obtained, corroborating the Lyα fluorescence as a key process to understand the Fe II spectrum. The best model was fine-tuned by applying a deconvolution method to the observed Fe II+Mg II spectrum. This derived semi-empirical template was then fitted to the spectrum of Ark 564, showing that it nicely reproduced its observed Fe II+Mg II emission. Our work extends the current set of available Fe II templates into the NIR region. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 0004637X
- Volume :
- 751
- Issue :
- 1
- Database :
- Academic Search Index
- Journal :
- Astrophysical Journal
- Publication Type :
- Academic Journal
- Accession number :
- 97977697
- Full Text :
- https://doi.org/10.1088/0004-637X/751/1/7