AI 中文总结
研究首次探测到PSR J2238+5903的射电脉冲，通过FAST的L波段观测及相关算法确认。利用观测数据得出其流量密度等信息，并用银河电子密度模型解释色散量得到距离，为评估1LHAASO J2238+5900性质提供了首个脉冲星特定距离约束。
AI 中文摘要
我们报告了首次探测到来自PSR J2238+5903的射电脉冲，它是一颗与扩展TeV源1LHAASO J2238+5900在空间上重合的伽马射线脉冲星。我们利用FAST进行了3000秒的L波段观测，发现了一个与已知费米大面积望远镜（Fermi-LAT）自旋周期相符的微弱周期性信号，其周期P = 162.76568毫秒，色散量DM = 247.5±3.0 pc cm⁻³。该信号通过基于快速傅里叶变换（FFT）和快速折叠算法的搜索得到独立确认。辐射计方程给出的流量密度S₁₂₅₀≈3 μJy，使PSR J2238+5903成为已探测到的最暗的费米射电脉冲星之一。用银河电子密度模型解释色散量得到距离d_DM = 7.4±3.9 kpc。在此距离下，LHAASO水切伦科夫探测器阵列（WCDA）39%的包含半径对应约132 pc的特征直径，大于1 TeV的光度L_TeV≈7.1×10³⁴ erg s⁻¹，约为脉冲星自转减慢功率的8%。因此，射电色散量为评估1LHAASO J2238+5900是否为年轻遗迹脉冲星风星云/TeV晕过渡系统提供了首个特定于脉冲星的距离约束。
英文摘要
We report the first detection of radio pulsations from PSR J2238+5903, a gamma-ray pulsar spatially coincident with the extended TeV source 1LHAASO J2238+5900. Our 3000 s FAST L-band observation reveals a weak periodic signal at the known Fermi-LAT spin period, with $P=162.76568$ ms and $\mathrm{DM}=247.5\pm3.0~\mathrm{pc~cm^{-3}}$. The signal is independently confirmed by both FFT-based and Fast Folding Algorithm searches. The radiometer equation gives a flux density of $S_{1250}\simeq3\,μ$Jy, placing PSR J2238+5903 among the faintest radio-detected Fermi pulsars. Interpreting the DM with Galactic electron-density models gives $d_{\rm DM}=7.4\pm3.9$ kpc. At this distance, the LHAASO WCDA 39\% containment radius corresponds to a characteristic diameter of $\sim132$ pc, and the $>1$ TeV luminosity is $L_{\rm TeV}\simeq7.1\times10^{34}$ erg s$^{-1}$, about 8\% of the pulsar's spin-down power. The radio DM thus provides the first pulsar-specific distance constraint for assessing whether 1LHAASO J2238+5900 is a young relic-PWN / TeV-halo transition system.
Comments8 pages, 2 figures, comments welcome
