Long-Term Optical and Spectral Variability of FSRQ 3C454.3

摘要

3C454.3 is a widely studied and monitored flat spectrum radio quasar. We use the observations from the Small and Moderate Aperture Research Telescope System (SMARTS) to analyze the long-term optical and spectral variabilities of 3C454.3 at B, V, R, J, and K (BVRJK) bands. Based on the relation , we calculate the multiband spectral indices () and analyze the relations between and , where is the flux density at band (=B, V, R, J, K). Main results are as follows. (1) The largest variations at BVRJK bands are B = 3.370.08 mag, with the timescale 1015 days, at B band; V = 3.310.07 mag, with the timescale 1014 days, at V band; R = 3.620.12 mag, with the timescale 679 days, at R band; J = 4.080.01 mag, with the timescale 763 days, at J band; and K = 5.030.03 mag, with the timescale 2715 days, at K band. (2) We analyze the long-term BVRJK lightcurves and obtain the quasiperiodicities days, days, and years. (3) Multiband lightcurves show time delays = days, = days, = days, and = days. (4) The relations between and show strong correlations, which are typical RWB behaviors; when the source turns to be brighter, the spectral indices turn to be redder.