http://arxiv.org/abs/1508.01723
New B and V band monitoring in 2014/2015 reveals that the Seyfert-1 galaxy 3C120 has brightened by 1.4 magnitudes compared to our campaign in 2009/2010. This allows us to check for the debated luminosity and time dependent color variations, claimed for SDSS quasars by Sun et al. (2014) based on an analysis in magnitude units. For our 3C120 data we find that the B/V flux ratio of the variable component in the bright epoch is indistinguishable from the faint one. We do not find any color variability on different timescales ranging from about 1 to 1800 days. We suggest that the luminosity and time dependent color variability by Sun et al. is an artifact caused by analyzing the data in magnitudes instead of fluxes. The flux variation gradients of both epochs yield consistent estimates of the host galaxy contribution to our 7.5″ aperture. These results corroborate that the optical flux variation gradient method works well for Seyfert Galaxies.
M. Ramolla, F. Nunez, C. Westhues, et. al.
Mon, 10 Aug 15
10/30
Comments: 8 pages, 6 figures. Accepted for publication in section 4. Extragalactic astronomy of Astronomy and Astrophysics
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