We present a detailed single pulse study of PSR B1055-52 based on observations at the Parkes radio telescope. The radio emission is found to have a complex modulation dominated by a periodicity of ~20 times its rotational period P (0.197s), whose phase and strength depends on pulse longitude. This periodicity exhibits a phase-locked delay of about 2.5P between the main pulse (MP) and interpulse (IP), presumed to be the opposite poles of the pulsar. This delay corresponds to a light travel distance of many times the light cylinder radius. More complex modulations are found within the MP on timescales down to about 9P, and both these and the principal modulation vary strongly across the (at least) 7 components which the MP and IP exhibit. The nature of the single pulse emission, which ranges from smooth and longitudinally extended to `spiky', is also component-dependent. Despite these disparities, the total pulse intensity distributions at the MP and IP are virtually identical in shape, suggesting a common emission mechanism. In an attempt to account for the complex modulations we examine a number of physical models, both intrinsic (which presuppose the pulsar to be an isolated neutron star) and extrinsic (appealing to the presence of circumstellar material to modulate the emission). Significant objections can be made to each model, so this pulsar's behaviour patterns remain a crucial challenge to theorists.
Modeling Multi-wavelength Pulse Profiles of Millisecond Pulsar PSR B1821-24
PSR B 1821 $-$ 24是一颗单毫秒脉冲星（MSP），辐射多波长脉冲光子。它具有复杂的无线电，X射线和$γ$射线脉冲轮廓，具有独特的峰值相位分离，挑战了传统的焦散辐射模型。采用单极环形隙模型，通过适当的磁倾角（$α=40^\circ$）和视角（$ζ=75^\circ$），我们成功地再现了它的三个波段的脉冲轮廓。结果表明，中间的射电峰起源于高海拔的核心间隙区，而另外两个射电峰则起源于相对低海拔的环形间隙区。X射线和$γ$射线波段的两个峰基本上都起源于环形间隙区，而从芯间隙区产生的$γ$射线发射对第一个$γ$射线峰有一定贡献。精确再现PSR B1821 $-$ 24的多波长脉冲轮廓使我们能够理解不同波段的发射区域，并证明脉冲星发射模型。
