Monitoring the Superorbital Period Excursion and the Spin Period Evolution of SMC X-1
In this talk, The speaker will introduce their work on exploring the connection between the spin and superorbital modulation of a bright accreting pulsar SMC X-1. The period of its superorbital modulation is highly variable. Hence, we use an advanced time-frequency analysis technique, the Hilbert-Huang transform, to characterize the excursion of the superorbital modulation period. They find that the major excursion event, for which the period evolves from 60 day to 40 day, is recurrent and likely (quasi-)periodic. With the help of MAXI, they are able to trace the evolution of the spin period semi-coherently. We obtain no significant positive correlation between the spin period residual and the superorbital frequency but observe a hint of anti-correlation. They also find that the superorbital profile changes during the excursion epoch. These new evidence are helpful for testing the models of the superorbital modulations.
講者：Dr. Chin-Ping Hu(京都大學天文系)