∼$6\%$ of all known pulsars have been observed to exhibit sudden spin-up events, known as glitches. For more than fifty years, these phenomena have played an important role in helping to understand pulsar (astro)physics. Based on the review of pulsar glitches search method, the progress made in observations in recent years is summarized, including the achievements obtained by Chinese telescopes. Glitching pulsars demonstrate great diversity of behaviours, which can be broadly classified into four categories: normal glitches, slow glitches, glitches with delayed spin-ups, and anti-glitches. The main models of glitches that have been proposed are reviewed and their implications for neutron star structure are critically examined regarding our current understanding. Furthermore, the correlations between glitches and emission changes, which suggest that magnetospheric state-change is linked to the pulsar-intrinsic processes, are also described and discussed in some detail.

The close correlation observed between emission state and spin-down rate change of pulsars has many implications both for the magnetospheric physics and the neutron star interior. The middle-aged pulsar PSR J0738−4042, which had been observed to display variations in the pulse profile associated with its spin-down rate change due to external effects, is a remarkable example. In this study, based on the 12.5-yr combined public timing data from UTMOST and Parkes, we have detected a new emission-rotation correlation in PSR J0738−4042 concurrent with a glitch. A glitch that occurred at MJD 57359(5) (December 3, 2015) with Δν/ν ∼ 0.36(4) × 10⁻⁹ is the first glitch event observed in this pulsar and is probably the underlying cause of the emission-rotation correlation. Unlike the usual post-glitch behaviours, the braking torque on the pulsar has continued to increase over 1380 d, corresponding to a significant decrease in |$\ddot{\nu }$|⁠. As for changes in the pulse profile after the glitch, the relative amplitude of the leading component weakens drastically, while the middle component becomes stronger. A combined model of crustquake induced platelet movement and vortex creep response is invoked to account for this rare correlation. In this scenario, magnetospheric state-change is naturally linked to the pulsar-intrinsic processes that give rise to a glitch.

PSR J1048$-$5832 (B1046$-$58) is a Vela-like pulsar that has exhibited multiple glitch events. In this study, we analyse the timing data spanning nearly 16 yr, acquired from both the Fermi Gamma-ray Space Telescope and the Parkes 64 m radio telescope. As a result, a total of five glitches are detected within this data set. Among them, a previously unknown small glitch is newly found at MJD 56985(9) (November 24, 2014), making it the smallest glitch recorded from this source so far. The increments of the spin frequency and its first derivative are $\Delta \nu \approx 2.2(3) \times 10^ {-8}$ Hz, and $\Delta \dot{\nu } \approx 3(2) \times 10^ {-15}$ s$^{-2}$, respectively. Significant changes in the integrated normalized mean pulse profile are detected following three of the five glitch events, notably in the radio band. Although no evidence of a correlation is found between the spin-down rate and profile evolution, the jump phenomenon of $W_{55}$ (pulse width at the 55% peak amplitude) after the glitch in the narrow mode suggests that the glitch may influence the profile change. We discuss the influence of glitches on the pulsar’s emission properties in terms of platelet motion by a crustquake and also put constraints on the equation of state from the moment of inertia and response time-scales of involved superfluid layers inside the neutron star.

Through a detailed timing analysis of Fermi-LAT data, the rotational behavior of the γ-ray pulsar PSR J1522−5735 was tracked from 2008 August (MJD 54692) to 2024 January (MJD 60320). During this 15.4 yr period, two overrecovery glitches and four antiglitches were identified, marking a rare occurrence in rotation-powered pulsars (RPPs). The magnitudes of these (net) spin-down glitches were determined to be ∣Δν _g/ν∣ ∼ 10⁻⁸, well above the estimated detectability limit. For the two overrecovery glitches, the respective recovery fractions Q are 2.1(7) and 1.4(2). Further analysis showed no substantial variations in either the flux or pulse profile shape in any of these events, suggesting that small (net) spin-down glitches, unlike large events observed in magnetars and magnetar-like RPPs, may occur without leaving an impact on the magnetosphere. Within the framework of the vortex creep and vortex bending models, antiglitches and overrecoveries indicate the recoupling of vortex lines that moved inward as a result of a crustquake; meanwhile, the apparent fluctuations in the spin-down rate after the glitches occur as a result of the coupling of the oscillations of bent vortex lines to the magnetosphere.

Pulsar glitch is a phenomenon characterized by abrupt changes in the spin period over less than a minute. We present a comprehensive analysis of glitches in four gamma-ray pulsars by combining the timing observation data from Fermi-Large Area Telescope (Fermi-LAT) and Parkes 64 m radio telescope. The timing data of five pulsars, namely PSRs J1028–5819, J1420–6048, J1509–5850, J1709–4429 (B1706–44), and J1718–3825, are examined over 14 yr of observations for each. A total of 12 glitches are identified in four pulsars, including a previously unreported glitch. That is, a new small glitch is identified for PSR J1718–3825 in MJD $\sim$ 59121(8), with a fractional glitch size of $\Delta \nu /\nu \sim 1.9(2) \times 10^{-9}$. For PSR J1420–6048, our investigation confirms the presence of two linear recovery terms during the evolution of $\dot{\nu }$ following glitches 4, 6, and 8. Moreover, an exponential recovery process was identified after glitch 8, with a recovery fraction (Q) of $Q = 0.0131(5)$ and a corresponding time-scale of $\tau _{\rm d} = 100(6)$ d. Regarding the fourth glitch of PSR J1709–4429, our analysis reveals the presence of two exponential recovery terms with degree of recovery and decay time-scales Q1 = 0.0104(5), $\tau _{\rm d1}=72(4)$ d, and Q2 = 0.006(1), $\tau _{\rm d2}=4.2(6)$ d, respectively. For the remaining previously reported glitches, we also refine the glitch epochs and recovery process through precise fitting of the timing data. We discuss how multiband data of glitches can help better characterize the glitch recoveries and constrain the underlying physics of glitch events. Our findings demonstrate that the accumulation of observational data reveals the rich complexity of the glitch phenomenon, aiding in the search for a well-established interpretation.

Anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs) are believed to be manifestations of magnetars. Typically, AXPs exhibit higher X-ray luminosities, whereas SGRs are generally fainter and display significantly high signal-to-noise ratios only during their outburst phases. In this work, we report the long-term timing evolution of four AXPs: 1E 2259+586, 4U 0142+61, 1RXS J170849.0–400910, and 1E 1841-045, which were regularly monitored with Neutron Star Interior Composition Explorer from 2017 to 2024. Over this period, we identify a total of 10 timing events. In addition to one glitch and one antiglitch in 1E 2259+586 reported in the literature, we detect another eight new timing events: five glitches, two antiglitches, and one unusual state transition event. Notably, both antiglitches were observed in 4U 0142+61, making it the most frequent source of such events, and there is a hint of regular evolution in its pulse profile. In the case of 1RXS J170849.0–400910, it continues to exhibit pronounced high-frequency timing anomalies and undergoes a state transition event. Finally, we study the evolution of the pulse profiles and find that the profiles of 1E 2259+586 and 4U 0142+61 both evolve. This is consistent with the earlier finding that pulse profile evolution is a generic feature of magnetars.