Abstract
Recent radio observations from some pulsars reveal abrupt emission variations that may be linked to changes in the magnetospheres. Further examinations show that most of these events, such as sudden changes of subpulse drift modes, quasi-periodic switching in emission between ‘on’ and ‘off’, and profile shape variations, are associated with changes in the slow-down rate of the pulsars, providing hints on the connections between the phenomena and the magnetospheric configuration. In addition, discernible timing noises that associated with variations in the arrival times of pulse profiles are seen from several pulsars when assuming the time of arrivals (ToAs) for each profile are exactly synchronized to the rotation period of the pulsar. These unusual emission features strongly suggest that multiple quasi-stable ‘emission states’ are allowed in pulsar magnetospheres, and that a pulsar can jump between different states.
In this preliminary talk, I will begin with an outline for a model on pulsar state switching, with additional geometric components, which lead to profile instability. I then illustrate the effects and implications of state switching on timing precision due to profile changes.
Coffee and tea will be served 20 minutes prior to the seminar.
Anyone interested is welcome to attend.