Past Events

Abstract
 

Pulsars are highly magnetized rotating neutron stars and radiate beams of emission that are observed as pulses when they sweep across the Earth. Their signature pulse shapes are so stable that high-precision studies of their rotation are possible. Often, pulsar timing can be predicted with a very simple model over many years with an accuracy of a few microseconds, or better. This accuracy provides us great chance to detect and measure very small perturbations embedded in the normal rotation of the star, and further extract information about processes inside and outside the pulsar. The differences of predicted arrival times of pulses and actual arrival times are known as pulsar timing residuals. If the timing model is perfect, timing residuals would be dominated by random measurement errors. Most common feature observed in the timing residuals is spin-down irregularities. Glitch as a main type of timing irregularity is characterized by a sudden increase in rotation rate followed by a period of relaxation, and mostly identified in the radio emission. Although glitches are very common in pulsars, a clear interpretation of this phenomenon is still missing. Here we choose several gamma-ray pulsars and analyze their high-energy emission before and after glitches. Through a comparison of flux, spectrum and pulse shape, we try to discuss the possible scenario of glitch.  

Anyone interested is welcome to attend.