Nine glitches in the Crab pulsar have been observed by pulsar group of Xinjiang Astronomical Observatory, including the largest glitch for this pulsar.

 

Pulsar glitches are characterized by the sudden increases in pulse frequency. Glitches are rather rare and unpredictable phenomena, and they vary significantly for different pulsars. The characteristics of glitches and the post-glitch recovery behavior provide an important diagnostic tool to study neutron star interiors. In order to study the glitch process, long-term monitoring of frequent glitching pulsars such as Crab and Vela are necessary.

 

Monitoring of radio emission from the Crab pulsar at Xinjiang Observatory detected a total of nine glitches during 2000 to 2010.

 

The occurrence of glitches appears to be a random process as described by previous researches. A persistent change in pulse frequency and pulse frequency derivative after each glitch was found. The pulsar suffered the largest frequency jump ever seen on 2004 March 3. The braking index presents significant changes. We attribute this variation to a varying particle wind strength which may be caused by glitch activities.