Abstract
We used Spitzer/Infrared Spectrograph spectroscopic data on 426 galaxies including quasars, Seyferts, LINERs, and Hii galaxies to investigate the relationship among the mid-IR emission lines. There is a tight linear correlation between the [Ne v]14.3 μm and 24.3 μm (97.1 eV) and the [Oiv]25.9 μm (54.9 eV) high-ionization emission lines. The correlation also holds for these high-ionization emission lines and the [Ne iii]15.56 μm (41 eV) emission line, although only for active galaxies. We used these correlations to calculate the [Ne iii] excess due to star formation in Seyfert galaxies. We also estimated the [Oiv] luminosity due to star formation in active galaxies and determined that it dominates the [Oiv] emission only if the contribution of the active nucleus to the total luminosity is below 5%. We find that the active galactic nucleus dominates the [Oiv] emission in most Seyfert galaxies, whereas star formation adequately explains the observed [Oiv] emission in optically classified Hii galaxies. Finally, we computed photoionization models to determine the physical conditions of the narrow-line region where these high-ionization lines originate. The estimated ionization parameter range is -2.8 < log U < -2.5 and the total hydrogen column density range is 20 < log nH (cm-2) < 21.
Original language | English (US) |
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Pages (from-to) | 2270-2280 |
Number of pages | 11 |
Journal | Astrophysical Journal |
Volume | 725 |
Issue number | 2 |
DOIs | |
State | Published - Dec 20 2010 |
Keywords
- Galaxies: active
- Galaxies: nuclei
- Galaxies: starburst
- Infrared: galaxies
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science
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Mid-IR emission lines in AGNs
Pereira-Santaella, M. (Creator), Diamond-Stanic, A. M. (Creator), Alonso-Herrero, A. (Creator) & Rieke, G. H. (Creator), Centre de Donnees Strasbourg (CDS), 2012
DOI: 10.26093/cds/vizier.17252270, https://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/725/2270
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