arXiv subjects

Jian-ping Yuan

Publications and source records attributed to Jian-ping Yuan.

3 recordsLinked to original sources

arXiv2025

A Rare Millisecond Pulsar with Cross-Pole Emission: Single-Pulse Insights from PSR J1857+0943

Studies of subpulse variability in millisecond pulsars (MSPs) offer important constraints on their emission physics. Using the high sensitivity of FAST, we present the first identification of distinct single pulse fluctuation behaviour in PSR J1857+0943. We find that the third component(MP\_C3) of the main pulse may originate from a different region than the other two main-pulse components and may instead share a common origin with the interpulse. This conclusion is supported by four observational evidence as follows: First, the LRCCF shows a clear anticorrelation between MP\_C3 and the interpulse. Second, the single-pulse polarization at the main-pulse longitude reveals obvious component mixing. Third, the modulation period of the interpulse components is roughly twice that of MP\_C3. Fourth, the reduced modulation index in MP\_C3 suggests possible mixing of emission from different regions. The interpretation in this letter contrasts with the usual assumption that the main pulse and interpulse originate from opposite magnetic poles. Hence, PSR J1857+0943 provides a rare laboratory for probing component-dependent plasma behaviour in an MSP magnetosphere. Our results offer direct evidence that the main pulse can include emission associated with more than one magnetic pole and highlight the importance of single-pulse diagnostics for understanding the geometry and dynamics of pulsars with interpulse emission. In addition, we analyse the jitter properties of this pulsar and measure a one-hour jitter of $σ_{J,1\rm h} = 78 \pm 3~\mathrm{ns}$ at 1.25 GHz, consistent with previous studies.

astro-ph.HE↗

arXiv2025

Results of 15-Year Pulsar Timing of PSR J0007+7303 with Fermi-LAT

The study of pulsar glitches provides a unique window into the internal structure and dynamic processes of neutron stars. PSR J0007+7303, a very bright gamma-ray pulsar, is the first pulsar discovered by the Fermi-LAT telescope. In this paper, we present the 15 years of timing results of this pulsar using the Fermi-LAT data. We identified nine glitches, five of which are newly discovered. Among these, two are small glitches, occurring between the three previously reported ones, while the other four are large glitches. The glitches exhibit fractional frequency changes ranging from 15 x 10^-9 to 1238 x 10^-9, with intervals of approximately 1-2 years between events. Uniquely, this pulsar shows no exponential recovery behavior following any glitch, setting it apart from most glitching pulsars. Furthermore, no significant changes were observed in the gamma-ray pulse profile, flux, or phase-averaged spectra before and after glitches, indicating the stability of the pulsar's emission properties despite internal changes. A parametric analysis of the glitches yielded a fractional moment of inertia of the crustal superfluid involved in glitches as 1.06 percent, which matches extremely well with previous statistical work if the non-dissipative entrainment effect is not considered and strongly supports the internal origin of these glitches. These results highlight the distinct glitch behavior of PSR J0007+7303 and offer valuable insights into the crust-superfluid interaction in neutron stars. The physical origin of no exponential recovery is also discussed.

astro-ph.HE↗

arXiv2012

VLBI astrometry of two millisecond pulsars

We present astrometric results on two millisecond pulsars, PSR B1257+12 and PSR J1022+1001, as carried out through VLBI. For PSR B1257+12, a model-independent distance of $710_{\rm -38}^{\rm +43}$ pc and proper motion of ($μ_{\rm α}=46.44\pm0.08$ mas/yr, $μ_{\rm δ}=-84.87\pm0.32$ mas/yr) were obtained from 5 epochs of VLBA and 4 epochs of EVN observations, spanning about 2 years. The two dimensional proper motion of PSR J1022+1001 ($μ_{\rm α} \sim -10.13$ mas/yr, $μ_δ \sim 16.89$ mas/yr) was also estimated, using 3 epochs of EVN observations. Based on our results, the X-ray efficiency of PSR B1257+12 should be in the same range as other millisecond pulsars, and not as low as previously thought.

astro-ph.SR↗