Discovery of Short-Term {\gamma}-Ray Pulsed Radiation Variations Following a Glitch in PSR J0205+6449

Abstract

Rotation-powered pulsars exhibit stable emission characteristics most of the time. However, their radiative state can vary with the sudden changes of rotational state such as glitches. To date, pulsed radiation changes associated with glitches have only been detected in the radio band. Since the emission regions of radio and $\gamma$-ray may differ, searching and investigating whether glitches can induce changes in high-energy radiation would further deepen our understanding of how glitches affect the magnetosphere of pulsars. We report successive variations in the $\gamma$-ray pulsed radiation of PSR J0205+6449 following the glitch at MJD 54904 observed by the {\sl Fermi}/LAT. The amplitude ratio of the two peaks showed a hint of an increase during MJD 54905--54940 initially, followed by a recovery to the mean level and a significant ($>5\,\sigma$) decrease in the separation between the two peaks over MJD 54940--55000. The amplitude ratio of the two peaks increased ($\sim3\,\sigma$) again in MJD 55000--55160, accompanied by a marginal flux variation. Finally, the pulsed radiation reverted to its normal state. This is the first significant detection of pulsed radiation variation associated with a glitch in $\gamma$-ray pulsars. We attribute this to magnetospheric reconfiguration triggered by localized crustal breaking and associated elastic displacement near the polar cap following the glitch.