A Possible Glitch in a Second Central Compact Object: PSR J0821-4300

Since 2009 we have been monitoring the timing behavior of the 112 ms PSR J0821–4300, the central compact object (CCO) in the supernova remnant Puppis A. Here we report analysis of these XMM-Newton and Chandra data up to 2021. There are significant timing residuals superposed on the steady spin-down, which can be described by various fits including one glitch, two glitches, or timing noise modelled with a frequency second derivative. We will compare the results to those for 1E 1207.4–5209, the first CCO observed to glitch, and to glitch activity and timing noise of pulsars in general. Although the origin of glitches is uncertain, their activity is correlated with spin-down rate. The detection of glitches in CCOs, surprising because they have a very small spin-down rate indicating a weak dipole magnetic field, may possibly be related to the slow reemergence of a stronger magnetic field that was initially buried by prompt fallback of supernova ejecta.