| Apresentação/Painel: | |
| Autor: | Rogério Riffel1 |
| Miriani G. Pastoriza1 | |
| Alex C. Carciofi2 | |
| Alberto Rodriguez-Ardila3 | |
| Charles J. Bonatto1 | |
| Instituição: | 1UFRGS - Porto Alegre |
| 2IAG/USP - São Paulo | |
| 3LNA/MCT - Itajubá | |
| Formato: | Painel |
| Título: | Near-Infrared Spectral Energy Distribution of Seyfert Galaxies |
| Resumo: | We employ IRTF SpeX NIR spectra to investigate the stellar population (SP), active galactic nuclei (AGN), featureless continuum (FC) and hot dust properties in 9 Sy 1 and 15 Sy 2 galaxies. Both the STARLIGHT code and the hot dust as an additional base element were used for the first time in this spectral range. Our synthesis shows significant differences between Sy 1 and Sy 2 galaxies: the hot dust component is required to fit the K-band spectra of ~90% of the Sy 1 galaxies, and only of ~25% of the Sy 2; about 50% of the Sy 2 galaxies require an FC component contribution > 20%; this fraction increases to about 60% in the Sy 1. In about 50% of the Sy2, the combined FC and young components contribute with more than 20%, while this occurs in 90% of the Sy1, suggesting recent star formation in the central region. The main results can be summarised as follows: (i) Our synthesis shows significant differences between Sy 1 and Sy 2 galaxies. The hot dust component is required to fit the K-band spectra of ~90% of the Sy 1 galaxies, and only of ~25% of the Sy 2; about 50% of the Sy 2 galaxies require an FC component contribution > 20%; this fraction increases to about 60% in the Sy 1. In about 50% of the Sy2, the combined FC and young components contribute with more than 20%, while this occurs in 90% of the Sy1, suggesting recent star formation in the central region. The main results can be summarised as follows: (i) Our synthesis shows significant differences between Sy 1 and Sy 2 galaxies. The hot dust component is required to fit the K-band spectra of ~ 80% of the Sy 1 galaxies, and only of ~40% of the Sy 2. Besides, about 50% of the Sy 2 galaxies require a featureless component contribution in excess of 20%, while this fraction increases to about 60% in the Sy 1. Also, in about 50% of the Sy 2, the combined FC and young components contribute with more than 20%, while this occurs in 90% of the Sy 1. This suggests recent star formation in the central region of our galaxy sample. (ii)For the 7 objects in common with previous optical studies, the NIR stellar population synthesis does not reproduce well the optical results. (iii) We found that the light at 1.223 micron-meters in central regions of the galaxies studied here contain a substantial fraction of intermediate-age SPs with a mean metallicity near solar. Moreover, our analysis confirms that the 1.1 micron-meters CN band can be taken as an unambiguous tracer of intermediate-age stellar populations. |
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