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For refcode 2007AJ....134.2006R:
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2007AJ....134.2006R The Mid-Infrared Emission of Seyfert Galaxies: A New Analysis of ISOCAM Data C. Ramos Almeida, A. M. Perez Garcia, J. A. Acosta-Pulido, and J. M. Rodriguez Espinosa Abstract. We present mid-infrared data of a sample of 57 AGNs obtained with the instrument ISOCAM on board the Infrared Space Observatory (ISO) satellite. The images were obtained through the LW2 (6.75 micron) and LW7 (9.62 micron) filters. This is a new analysis of the Clavel et al. galaxy sample, which is divided into 26 type 1 (<=1.5) and 28 type 2 (>1.5) Seyfert galaxies, plus three QSOs. The spatial resolution of the images allows us to separate the nuclear and the extended contributions to the total emission after decomposing the brightness profiles into different morphological components. The most common components are a central point source (identified as the active nucleus) and an exponential disk. In some cases a bulge, a bar, or a ring are needed. The relative contribution of the nucleus to the total emission appears larger in Seyfert 1 than in Seyfert 2 types. This result confirms that both types of Seyfert galaxies are different in the mid-infrared wavelength range and supports the existence of a structure which produces anisotropic emission in this wavelength range. We have also explored correlations between the mid-infrared and the radio and X-ray wavelength ranges. The well-established radio/infrared correlation is maintained in our sample for the global emission of the galaxies. If only the nuclear infrared emission is considered, then a nonlinear correlation is apparent in the luminosity-luminosity scatter diagram. The ratio between the intrinsic hard X-ray and the nuclear mid-infrared emission presents large scatter and slightly larger values for type 2 Seyfert galaxies. These results seem to be consistent with the presence of a clumpy dusty torus surrounding the active nucleus. ========================================================================== 2008AJ....135.1657R ERRATUM: "THE MID-INFRARED EMISSION OF SEYFERT GALAXIES. A NEW ANALYSIS OF ISOCAM DATA*" (2007, AJ, 134, 2006) C. Ramos Almeida, A. M. Perez Garcia, J. A. Acosta-Pulido and J. M. Rodriguez Espinosa In our original paper (Section 4.4) we compared the ratios of hard X-ray to nuclear mid-infrared emission for Seyfert 1 and 2 (Sy1 and Sy2) nuclei, finding that both distributions appear significatively different according to the Kolmogorov-Smirnov test. We have detected a mistake in the computation of the X-ray luminosities (the lack of a 4{pi} factor). Additionally, for two galaxies, the nuclear mid-infrared fluxes used within calculations are slightly different from the correct values which are reported in Table 3 of the original version. These mistakes affect the mentioned ratios of hard X-ray to nuclear mid-infrared emission, although they do not alter the result concerning the distributions, being statistically different. The correct values of these ratios are <log(L ^X^_intr_/L ^MIR^)> = -0.21 +- 0.33 for the Seyfert 1 galaxies, and <log(L ^X^_intr_/L ^MIR^)> = 0.17 +- 0.62 for the type 2 nuclei. Figure 8 has been updated with the newly computed values. We have also corrected the X-axis with respect to the original figure, which is now {nu} L _{nu}_. We have performed again Spearman's rank correlation test, finding that the correlation is significant when all galaxies and types 1 and 2 are considered separately. It is worthwhile to note that here we have excluded from the analysis two Seyfert 2 galaxies (NGC 1386 and NGC 7674) due to their extremely low hard X-ray luminosities, consistent with being optically thick sources. Recently, Horst et al. (2008) have estimated an intrinsic X-ray luminosity for NGC 7674 of log L ^X^_intr_ = 44.56 erg s^-1^, in contrast to the non-absorption-corrected value reported by Lutz et al. (2004) (log L^X^_obs_ = 41.91 erg s^-1^). Such a difference of about 2.5 dex corroborates our decision of not including these galaxies. {see figure 8} In a recent work, Horst et al. (2008) have argued that our luminosity ratios are ~8 larger than what they have found for their well-resolved objects, claiming that our nuclear data are heavily contaminated by nuclear star formation. Our new values are now of the same order of magnitude than theirs, even smaller for the case of Seyfert 2 galaxies. Therefore, we believe that despite the limited resolution of ISOCAM images, our nuclear fluxes are representative of the torus emission, and the contamination by circumnuclear star formation, although present, is not dominant. There is a typographical mistake in Table 3 for the point-spread function (PSF) flux in the LW7 filter corresponding to the galaxy ESO144-G55; the correct value is 84.2 +- 2.44 mJy. ===========================================================================
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