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The two component model of neutron star dynamics describing the behaviour of the observed crust coupled to the superfluid interior has so far been applied to radio pulsars for which the external torques are constant on dynamical timescales. We recently solved this problem under arbitrary time dependent external torques. Our solutions pertain to internal torques that are linear in the rotation rates, as well as to the extremely non-linear internal torques of the vortex creep model. Two-component models with linear or nonlinear internal torques can now be applied to magnetars and to neutron stars in binary systems, with strong variability and timing noise. Time dependent external torques can be obtained from the observed spin-down (or spin-up) time series, Ω ˙ ( t ) .

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.

We present a comprehensive single-pulse study of three pulsars, namely PSRs J1854–0036, J2159+0202, and J2112+0740, discovered by the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in the Commensal Radio Astronomy FAST Survey (CRAFTS). We observe that these pulsars display different kinds of single-pulse phenomena, bearing implications for pulse emission mechanisms and geometry. PSR J1854–0036 exhibits quasiperiodic nulling with a nulling fraction of 31% ± 1% and a periodicity of (127.4 ± 0.4)P (where P is the spin period of the pulsar). We identified a weak emission in the null profile, suggesting either a global magnetospheric state switching or a change in geometric orientation rather than complete cessation of emission. PSR J2159+0202 exhibits complex subpulse drifting or intensity modulations with periodicities ranging from P3 = (7.0 ± 0.2)P to (10.9 ± 0.1)P. PSR J2112+0740 exhibits burst-like radiation without evidence of nulling or coherent subpulse drifting, potentially associated with stochastic pair production or plasma instabilities within the pulsar’s emission region. These results highlight the multiscale nature of the pulsar emission, potentially linking nulling, drifting, and erratic radiation to different magnetospheric processes.

We report on a single-pulse study of PSR J1239+0326 discovered by the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in the Commensal Radio Astronomy FAST Survey. The observations were conducted at a central frequency of 1.25 GHz. The integrated pulse profile of PSR J1239+0326 shows four distinct components, implying a central line of sight traversing a presumed double cone core emission beam. We found correlations between intensities of the first and fourth components and the second and the core components, indicating that the charges emitted between the correlated components may be related. Based on rotating vector model fitting, we estimated the inclination angle between the magnetic and the rotational axes to be 10°. No nulls, giant pulses, or giant micropulses were detected during observation sessions. Outer-cone components are observed to display “even-odd” subpulse modulation with quasiperiodicity around 2P, where P is the rotational period of the pulsar. The trailing component exhibits energy modulation with quasiperiodicities of 19P and 26P. This two-mode modulation could result from the combination of sub-pulse drifts and the feedback between the voltage difference across the polar gap and surface thermal emission by backflowing charges.

The existing single-pulse search algorithms for fast radio bursts (FRBs) do not adequately consider the frequency bandpass pattern of the pulse, rendering them incomplete for the relatively narrow-spectrum detection of pulses. We present a new search algorithm for narrowband pulses to update the existing standard pipeline, Bandpass-Adaptive Single-pulse SEarch Toolkit (BASSET). The BASSET algorithm employs a time–frequency correlation analysis to identify and remove the noise involved by the nondetection frequency band, thereby enhancing the signal-to-noise ratio (SNR) of the pulses. The BASSET algorithm was applied to the FAST real data set of FRB 20190520B, resulting in the discovery of additional 79 pulses through reprocessing. The new detection doubles the number of pulses compared to the previously known 75 pulses, bringing the total number of pulses to 154. In conjunction with the pulse calibration and the Markov Chain Monte Carlo simulated injection experiments, this work updates the quantified parameter space of the detection rate. Moreover, a parallel-accelerated version of the BASSET code was provided and evaluated through simulation. BASSET has the capacity of enhancing the detection sensitivity and the SNR of the narrowband pulses from the existing pipeline, offering high performance and flexible applicability. BASSET not only enhances the completeness of the low-energy narrowband pulse detection in a more robust mode, but also has the potential to further elucidate the FRB luminosity function at a wider energy scale.

Polarization measurements of fast radio bursts (FRBs) probe the magnetized plasma surrounding their central engines. FRB 20240114A is an exceptionally active repeating source, with 17,356 bursts detected between 2024 January 28 and 2025 May 30 by FAST, enabling studies of the temporal evolution of its polarization properties. In this work, we present a polarimetric catalog of 6131 bright bursts (with a signal-to-noise ratio (S/N) ≥ 20, 35.3% of the total sample), including arrival time (MJDtopo), dispersion measure (DM), burst width (Weff), bandwidth, Faraday rotation measure (RM), linear and circular polarization degrees (L/I, V/I), and intrinsic polarization angle (PA0). We confirm a clear temporal evolution of RM: after an initial stable phase, it decreases linearly by ∼200 rad m−2 over 200 days, forming a bimodal distribution, whereas DM remains stable at 529.3 ± 1.2 pc cm−3. The linear polarization fraction is generally high, with the 3σ lower bound around 76%, while circular polarization is low, with 1157 of 17,356 bursts (6.67%) having ∣V∣/I ≥ 10%. We perform a power-law fit between ∣V∣/I and ∣RM∣, which yields an index of −2.98 ± 0.80. It is found that the combined 2D distribution of L/I versus V/I remains stable, implying that the emission mechanism is largely invariant. Our PA0 measurements show a broad, nonuniform distribution, implying a complex emission geometry. These results suggest that FRB 20240114A resides in a dynamically evolving magneto-ionic environment. This catalog provides a foundation for studies of repeating FRB progenitors and their environments.

Polarization measurements of fast radio bursts (FRBs) probe the magnetized plasma surrounding their central engines. FRB~20240114A is an exceptionally active repeating source, with 17,356 bursts detected between 2024 January 28 and 2025 May 30 by FAST, enabling time-resolved polarimetric studies. In this work, we present a polarimetric catalog of 6,131 bright bursts (with a signal-to-noise ratio S/N \\(\\) 20, 35.3% of the total sample), including arrival time (MJD\\(_topo\\)), dispersion measure (DM), burst width (W\\(_eff\\)), bandwidth, Faraday rotation measure (RM), linear and circular polarization degrees (DOL, DOC), and intrinsic polarization angle (PA\\(_0\\)). We detect a clear temporal evolution of RM: after an initial stable phase, it decreases linearly by \\(\\)200 \\( rad\\ m^-2\\) over 200 days, forming a bimodal distribution, whereas DM remains stable at 528.9 \\( pc\\ cm^-3\\). The linear polarization fraction is generally high, with the 3\\(\\) lower bound around 76%, while circular polarization is low, with 1,157 of 17,356 bursts (6.67%) having DOC \\(\\)10%. We perform a power-law fit between \\(|V|\\)/I and \\(|RM|\\), which yields an index of \\(-2.98 0.80\\). It is found that the combined 2D distribution of L/I versus V/I remains stable, implying that the emission mechanism is largely invariant. Our PA\\(_0\\) measurements show a broad, non-uniform distribution, implying a complex emission geometry. These results suggest that FRB~20240114A resides in a dynamically evolving magneto-ionic environment. This catalog provides a foundation for studies of repeating FRB progenitors and their environments.

The origin of fast radio bursts (FRBs), the brightest cosmic radio explosions, is still unknown. Bearing critical clues to FRBs' origin, the long-term evolution of FRBs has yet to be confirmed, since the field is still young and most FRBs were seen only once. Here we report clear evidence of decadal evolution of FRB~20121102A, the first precisely localized repeater. In conjunction with archival data, our FAST and GBT monitoring campaign since 2020 reveals a significant 7% decline of local dispersion measure (DM). The rotation measure (RM) of 30,755\\(\\)16 \\(rad\\,m^-2\\) detected in the last epoch represents a 70% decrease compared to that from December 2016. The \\(_RM\\) parameter, which describes the complexity of the magneto-ionic environment surrounding the source, was shown to have decreased by 13%. These general trends reveal an evolving FRB environment, which could originate from an early-phase supernova associated with an enhanced pair wind from the FRB central engine.

We present timing solutions from the Fermi-LAT observations of gamma-ray pulsars PSR J0835\\(-\\)4510 (Vela), PSR J1023\\(-\\)5746, PSR J2111\\(+\\)4606, and PSR J2229\\(+\\)6114. Data ranges for each pulsar extend over a decade. From data analysis we have identified a total of 20 glitches, 11 of which are new discoveries. Among them, 15 glitches are large ones with \\(/10^-6\\). PSR J1023\\(-\\)5746 is the most active pulsar with glitch activity parameter being \\(A_ g=14.510^-7\\)~in the considered data span and should be a target for frequently glitching Vela-like pulsars in future observations. We have done fits within the framework of the vortex creep model for 16 glitches with \\(/10^-7\\). By theoretical analysis of these glitches we are able to obtain important information on the structure of neutron star, including moments of inertia of the superfluid regions participated in glitches and coupling time-scales between various stellar components. The theoretical prediction for the time to the next glitch from the parameters of the previous one is found to be in qualitative agreement with the observed inter-glitch time-scales for the considered sample. Recoupling time-scales of the crustal superfluid are within the range of theoretical expectations and scale inversely with the spin-down rate of a pulsar. We also determined a braking index n=2.63(30) for PSR J2229\\(+\\)6114 after glitch induced contributions have been removed.

PSR J1048\\(-\\)5832 (B1046\\(-\\)58) is a Vela-like pulsar that has exhibited multiple glitch events. In this study, we analyze the timing data spanning nearly 16 years, 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 dataset. 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 \\( 2.2(3) 10^ -8 \\) Hz, and \\( 3(2) 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 timescales of involved superfluid layers inside the neutron star.