Zhi-Gang Wen’s research while affiliated with Xinjiang Astronomical Observatory and other places

UTC(k) can be considered a shorthand for the local time standard maintained by a country's or region's time‐ frequency laboratory. Each lab uses its local atomic clocks to maintain this standard and synchronizes it with Coordinated Universal Time (UTC). Although local atomic clocks can operate independently, they generally rely on UTC as a reference standard for precision and long‐term stability. To effectively monitor local atomic clocks and improve monitoring efficiency, this paper aims to study new monitoring methods from the perspective of macroscopic astrometry. By utilizing the measurement results of millisecond pulsars and combining them with clock models, this paper focuses on calculating and predicting the deviation data of local atomic clocks. This method not only expands the means of monitoring local atomic clocks but also has significant implications for improving monitoring accuracy and reliability. To validate its effectiveness, we first calculate and analyze the actual and simulated data of millisecond pulsars, then compare the analysis results with the conventional clock deviation data of local clocks based on UTC as a reference. The results indicate that using millisecond pulsars for monitoring can feasibly obtain the phase and frequency deviations of local atomic clocks within a 95% confidence interval. This demonstrates the feasibility of this method. Therefore, monitoring local atomic clocks using millisecond pulsars is reliable and effective. This study provides new insights and methods for the monitoring of local clocks and is significant for improving monitoring accuracy and reliability.

We report the radio observations of the eclipsing black widow pulsar J1720-0534, a 3.26 ms pulsar in orbit with a low mass companion of mass 0.029 to 0.034 M$_{\odot}$. We obtain the phase-connected timing ephemeris and polarization profile of this millisecond pulsar (MSP) using the Five-hundred-meter Aperture Spherical Radio Telescope (FAST), the Green Bank Telescope (GBT), and the Parkes Telescope. For the first time from such a system, an oscillatory polarisation angle change was observed from a particular eclipse egress with partial depolarization, indicating 10-milliGauss-level reciprocating magnetic fields oscillating in a length scale of 5000 km (assuming an orbital inclination angle of 90 degrees) outside the companion's magnetosphere. The dispersion measure variation observed during the ingresses and egresses shows the rapid raising of the electron density in the shock boundary between the companion's magnetosphere and the surrounding pulsar wind. We suggest that the observed oscillatory magnetic fields originate from the pulsar wind outside the companion's magnetosphere.

PSR J0742−2822 is known for its quasi-periodic changes in the observed pulse profile and spindown rate. In this paper, we analyzed 13 years of timing data obtained with the Nanshan 25-m radio telescope and the Parkes 64-m radio telescope. We found that the average values of the spin-down rate ( 〈 ν ˙ 〉 ) of this pulsar changed in four different states. We investigated the correlation between ν ˙ and W 50 , and ascertained that the correlation changed in different 〈 ν ˙ 〉 states. Moreover, not all the changes in 〈 ν ˙ 〉 states and correlation can be associated with glitch activities. We examined the long term evolution of γ -ray flux (0.1–300 GeV) and the pulse profiles corresponding to the four different states using Fermi-LAT Pass 8 (P8R3) data from 2008 August 5 to 2019 October 1. We did not detect a significant change in γ -ray flux or the pulse profile. Our results suggest that the connection between pulsar rotation and emission is more complex than previously reported for this pulsar.