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Long-term spectral variability of NGC 4151 (Shapovalova+, 2008)статья
- Авторы: Shapovalova A.I., Popovic L.C., Collin S., Burenkov A.N., Chavushyan V.H., Bochkarev N.G., Benitez E., Dultzin-Hacyan D., Kovacevic A., Borisov N., Carrasco L., Leon-Tavares J., Mercado A., Valdes J.R., Vlasuyk V.V., Zhdanova V.E.
- Журнал: VizieR Online Data Catalog
- Том: 348
- Год издания: 2008
- Первая страница: 60099
- Аннотация: Results of a long-term spectral monitoring of the active galactic nucleus of NGC 4151 are presented (11 years, from 1996 to 2006). High quality spectra (S/N\gt50 in the continuum near Hα and H$$beta$$) were obtained in the spectral range ~4000 to 7500$$AA$$, with a resolution between 5 and 15 $$AA$$, using the 6-m and the 1-m SAO’s telescopes (Russia), the GHAO’s 2.1-m telescope (Cananea, Mexico), and the OAN-SPM’s 2.1-m telescope (San-Pedro, Mexico). The observed fluxes of the Hα, H$$beta$$, H$$gamma$$ and HeII$$lambda$$4686 emission lines and of the continuum at the observed wavelength 5117$$AA$$, were corrected for the position angle, the seeing and the aperture effects. We found that the continuum and line fluxes varied strongly (up to a factor 6) during the monitoring period. The emission was maximum in 1996-1998, and there were two minima, in 2001 and in 2005. As a consequence, the spectral type of the nucleus changed from a Sy1.5 in the maximum activity state to a Sy1.8 in the minimum state. The Hα, H$$gamma$$ and He$$lambda$$4686 fluxes were well correlated with the H$$beta$$ flux. The line profiles were strongly variable, showing changes of the blue and red asymmetry. The flux ratios of the blue/red wings and of the blue (or red) wing/core of Hα and H$$beta$$ varied differently. We considered three characteristic periods during which the H$$beta$$ and Hα profiles were similar: 1996-1999, 2000-2001 and 2002-2006. The line to continuum flux ratios were different; in particular during the first period (1996-2001), the lines were not correlated with the continuum and saturated at high fluxes. In the second and third period (2002-2006), where the continuum flux was small, the Hα and H$$beta$$ fluxes were well correlated to the continuum flux, meaning that the ionizing continuum was a good extrapolation of the optical continuum. The CCFs are often asymmetrical and the time lags between the lines and the continuum are badly defined indicating the presence of a complex BLR, with dimensions from a 1 to 50 light-days. We discuss the different responses of H$$beta$$ and Hα to the continuum during the monitoring period. (4 data files).
- Добавил в систему: Бочкарев Николай Геннадиевич