Optical Photometry of the Quasar 3C 454.3 during the Period 2006-2018 and the Long-term Periodicity Analysis

In this work, we present 8523 pairs of R-band optical photometry observations for the quasar 3C 454.3 made during the period of 2006 October-2018 February on the 70 cm meniscus telescope at Abastumani Observatory, Georgia, to study its intraday variabilities (IDVs) and long-term variations, and we have come to the following results. (1) We detected 10 outbursts, a ΔR = 3.825 mag variation, and some IDVs. The IDV timescales are from 4.1 to 285 minutes, with the corresponding variability amplitude being A = 2.9%-43.67%. The amplitude increases with IDV timescale. (2) The largest variation over a 1 day timescale is ΔR = 1.38 mag. (3) The IDV timescales suggest that the emission sizes are from 8.9 × 10¹³ cm to 6.20 × 10¹⁵ cm, and the magnetic field strengths are B = 0.18-0.79 G. (4) Period analysis results show three possible long-term periods, p = 3.04 ± 0.02 yr, p = 1.66 ± 0.06 yr, and p = 1.20 ± 0.03 yr in the optical light curve. We adopted the accretion disk models and the lighthouse models to period p = 3.04 ± 0.02 yr: in the accretion disk models, the binary black holes have masses M = 1.17 × 10⁹ M _⊙ in the lighthouse models, we used two boosted jet flux densities to fit the observational light curve. (5) WWZ analysis gives some short-period (high-frequency) signals associated with strong bursts (JD 2,454,302 and JD 2,454,521) with variable frequencies and lasting for the entire observation time span (11.3 yr).