The Research on the Profile Stability of the Millisecond Pulsar PSR J1022+1001

Pulsars, especially the millisecond pulsars, have very stable integrated pulse profiles. Previous studies found that the integrated pulse profiles of some pulsars exhibit instabilities. In this article, the stability of the integrated pulse profile of millisecond pulsar PSR J1022 +1001 is investigated. The profile has two peaks, and it is found that the peak ratio significantly changes with time. It is concluded from the analysis that the integrated pulse profile instability of the millisecond pulsar is mainly due to the evolution of the pulse profile with frequency, and in the meanwhile the flux density variations at different frequencies are caused by the interstellar scintillation. It is also found that a small part of integrated pulse profile instability may be due to the intrinsic pulsar properties or other factors.