Unique Photometric Variability in SDSS J134628.62+173659.5: Clues for Moving Dust Clouds as the Physical Origin of Changing-look Active Galactic Nuclei

The scenario of variations in the accreting process around the central black hole has been widely accepted as the preferred physical origin of changing-look active galactic nuclei (CLAGN), rather than the obscuration effects of moving dust clouds being the origin. In this paper, after analyzing long-term photometric variability in type-1.8 AGN SDSS J1346+1736 with apparent broad H α but very weak broad H β , robust clues of obscurations can be confirmed with a confidence level higher than 10 σ . Based on obscurations related to moving dust clouds, from a dark state with E ( B − V ) ∼ 1.26 to a bright state with E ( B − V ) ∼ 0.55, both apparent broad H α and broad H β can be clearly expected. Meanwhile, the expected line luminosity from the reddening-corrected continuum luminosity is consistent with the reddening-corrected line luminosity to support the obscuration effects. Furthermore, through symmetric features in the light curves, the probability is only 3.2% in SDSS J1346+1736 to support the scenario of variations of accretion rates traced by CAR process. Therefore, besides the more and more preferred scenario of variations in accreting process, the scenario of moving dust clouds could be more reasonable in some CLAGN with apparent variations in optical colors.