The Period Analysis for Quasar 3C 273 in the Optical Band

The data of the quasar 3C 273 in optical band have been accumulated for nearly 100 years. Based on the obtained light curve, we analyzed the periodicity of its light variation using the Period04 software. It is found that there are three periods in the light curve, including 2.06 yr, 13.03 yr, and 21.15 yr. These are basically consistent with the conclusion of Fan et al., that the periods of 3C 273 in the optical B-band are 2.0 yr, (13.65 ± 0.20) yr, and (22.5 ± 2.0) yr. Then, a period inversion was made by fitting the observed data with the three periods, as a result, the features of the fitting curve and the outbursts in the observed data are basically consistent, indicating the three periods are reliable. And by its long period, the mass of the central black hole was derived to be M = 1.87 × 106M⊙. Finally, we discussed its central black hole mass, and the possible mechanisms responsible for its light periods.