A Long-Term Rotational Anomaly in the Crab Pulsar Following the 2011 November Glitch

The Crab pulsar’s rotation history has been well characterized by a long-term spin-down, occasional glitches, and timing noise. Previous studies established that glitches follow a prototypical recovery: an instantaneous ν˙ jump followed by a quasi-exponential relaxation on ∼320 days. Using monthly frequency data from the Jodrell Bank ephemeris, we construct timing residuals (δν) and apply segmented linear fitting to track the evolution of their slope. We focus on the period from MJD 56427 to MJD 57827 (May 2013–March 2017), covering the anomalous phase that began approximately 1200 days after the 2011 November glitch (MJD 55875.5 to MJD 57075). Our results show a persistent departure from the Lyne model: the segmented slope shows a persistent increasing trend from 2.664±0.304 to 20.949±1.51 (in 10−15 Hz s−1) over ∼700 days—opposite to the decreasing trend expected from thermal recovery. This deviation is statistically significant and shows no sign of returning to the model curve. We conclude that the standard glitch recovery paradigm does not fully capture the long-term behaviour of the Crab pulsar. The anomaly cannot be explained by a simple thermal relaxation process and may point towards a persistent change in magnetospheric torque or long-term internal dynamics.