Astrophys. J., 689, 95-107 (2008/December-2)
Constraining the active galactic nucleus contribution in a multiwavelength study of Seyfert galaxies.
MELENDEZ M., KRAEMER S.B., SCHMITT H.R., CRENSHAW D.M., DEO R.P., MUSHOTZKY R.F. and BRUHWEILER F.C.
Abstract (from CDS):
We have studied the relationship between the high- and low-ionization [O IV] λ25.89 µm, [Ne III] λ15.56 µm, and [Ne II] λ12.81 µm emission lines with the aim of constraining the active galactic nuclei (AGNs) and star formation contributions for a sample of 103 Seyfert galaxies. We use the [O IV] and [Ne II] emission as tracers for the AGN power and star formation to investigate the ionization state of the emission-line gas. We find that Seyfert 2 galaxies have, on average, lower [O IV]/[Ne II] ratios than Seyfert 1 galaxies. This result suggests two possible scenarios: (1) Seyfert 2 galaxies have intrinsically weaker AGNs, or (2) Seyfert 2 galaxies have relatively higher star formation rates than Seyfert 1 galaxies. We estimate the fraction of [Ne II] directly associated with the AGNs and find that Seyfert 2 galaxies have a larger contribution from star formation, by a factor of ∼1.5 on average, than what is found in Seyfert 1 galaxies. Using the stellar component of [Ne II] as a tracer of the current star formation, we found similar star formation rates in Seyfert 1 and Seyfert 2 galaxies. We examined the mid- and far-infrared continua and found that [Ne II] is well correlated with the continuum luminosity at 60 µm and that both [Ne III] and [O IV] are better correlated with the 25 µm luminosities than with the continuum at longer wavelengths, suggesting that the mid-infrared continuum luminosity is dominated by the AGN, while the far-infrared luminosity is dominated by star formation. Overall, these results test the unified model of AGNs and suggest that the differences between Seyfert galaxies cannot be solely due to viewing angle dependence.
Galaxies: Seyfert - Galaxy: Stellar Content - Infrared: Galaxies
Table 1: MRK 1034 NED02 = MRK 1034A in SIMBAD, MRK 1034 NED01 = MRK 1034B in SIMBAD.
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