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Monitoring the Superorbital Period Excursion and the Spin Period Evolution of SMC X-1


Speaker:Dr. Chin-Ping Hu
Affiliation:Department of Astronomy, Kyoto University
Date:May 24, 2019 (Friday)
Time:11:30 a.m.
Venue:Room 522, 5/F, Chong Yuet Ming Physics Building, HKU

Abstract


In this talk, I will introduce our 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. We 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, we 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. We also find that the superorbital profile changes during the excursion epoch. These new evidence are helpful for testing the models of the superorbital modulations.

Coffee and tea will be served 20 minutes prior to the seminar.

Anyone interested is welcome to attend.