The 2016 glitch in the Vela pulsar

We report the detection of a glitchevent in the Velapulsar, which occurred on 12 December 2016, based on the timing data obtained from observations between January 2016 and February 2018 at frequency centered at 2256 MHz using the Kunming 40-m radio telescope. The timing solutions for the pre- and post- glitchare presented. By fitting the glitchmodel to the timing data, we found that the post- glitchrecovery exhibits two terms with exponential decaywith the time scales of 1 d and 6 d, respectively. The glitchparameters are determined with \(\Delta \nu _{\mathrm{g}}/\nu =1.431(2)\times 10^{-6}\) and \(\Delta \dot{\nu }_{\mathrm{g}}/\dot{\nu }=73.354\times 10^{-3}\). The value of the coupling parameteris calculated to be ∼0.08, implying that the core superfluid is probably not involved in this event. For the glitcheswith two or more terms with exponential decayin the Velapulsar, we show that the exponential decaysusually exhibit longer time scales with higher degree of glitchrecovery. The post- glitchbehavior in the slow-down rate \(|\dot{\nu }|\) is dominated by a linear decrease process. From detection of the variations in the slopes of the spin-down rates after the exponential recoveries of the 2013 and 2016 glitches, we conclude that no persistent shift was involved in the 2016 glitches.