标题： LMC中的蟹状脉冲星X射线/GeV发射 显示英文标题

标题： X-ray/GeV emissions from Crab-like pulsars in LMC

摘要： 我们讨论了来自船帆座脉冲星相似的脉冲星 PSRs J0537-6910 和 J0540-6919 的X射线和伽马射线辐射，这些脉冲星位于大麦哲伦云中。费米伽马射线空间望远镜（Fermi-LAT）的观测已经分辨出这两个脉冲星的伽马射线辐射，并且发现了来自 PSR J0540-6919 的脉冲辐射。PSR J0540-6919 在 X 射线/伽马射线能量带中的总脉冲辐射效率为$\eta_{J0540}\sim 0.06$（在 4$\pi$立体角内），大约是蟹状脉冲星效率$\eta_{Crab}\sim 0.006$的十倍。尽管 PSR J0537-6910 是目前已知脉冲星中自转减速功率最高的，但其观测到的 X 射线辐射效率比 PSR J0540-6919 低两个数量级。本文主要探讨导致这三个高能船帆座脉冲星辐射效率差异的原因。我们在外间隙模型中讨论电子/正电子加速以及高能辐射过程。通过求解偶极磁场下的外间隙结构，我们表明随着磁轴与旋转轴之间的倾角增大，辐射效率会减小。为了说明脉冲轮廓和辐射效率的差异，我们的模型提出 PSR J0540-6919 的倾角远小于蟹状脉冲星的倾角（这里假设两者的倾角分别为$\alpha<90^{\circ}$）。另一方面，我们推测 PSRs J0537-6910 和 J0549-6919 之间辐射效率的差异主要是由于地球观测角度的不同，即我们从自旋轴测量的角度看到 PSR J0537-6910 为$\zeta>>90^{\circ}$（或$<<90^{\circ}$），而看到 PSR J0540-6919 为$\zeta\sim 90^{\circ}$。 显示英文摘要

摘要： We discuss X-ray and gamma-ray emissions from Crab-like pulsars, PSRs~J0537-6910 and~J0540-6919, in Large Magellanic Cloud. Fermi-LAT observations have resolved the gamma-ray emissions from these two pulsars and found the pulsed emissions from PSR~J0540-6919. The total pulsed radiation in the X-ray/gamma-ray energy bands of PSR~J0540-6919 is observed with the efficiency $\eta_{J0540}\sim 0.06$ (in 4$\pi$ sr), which is about a factor of ten larger than $\eta_{Crab}\sim 0.006$ of the Crab pulsar. Although PSR~J0537-6910 has the highest spin-down power among currently known pulsars, the efficiency of the observed X-ray emissions is about two orders of magnitude smaller than that of PSR~J0540-6919. This paper mainly discusses what causes the difference in the radiation efficiencies of these three energetic Crab-like pulsars. We discuss electron/positron acceleration and high-energy emission processes within the outer gap model. By solving the outer gap structure with the dipole magnetic field, we show that the radiation efficiency decreases as the inclination angle between the magnetic axis and the rotation axis increases. To explain the difference in the pulse profile and in the radiation efficiency, our model suggests that PSR~J0540-6919 has an inclination angle much smaller than the that of Crab pulsar (here we assume the inclination angles of both pulsars are $\alpha<90^{\circ}$). On the other hand, we speculate that the difference in the radiation efficiencies between PSRs~J0537-6910 and J0549-6919 is mainly caused by the difference in the Earth viewing angle, and that we see PSR~J0537-6910 with an Earth viewing angle $\zeta>>90^{\circ}$ (or $<<90^{\circ}$) measured from the spin axis, while we see PSR~J0540-6919 with $\zeta\sim 90^{\circ}$.