标题： 利用SKA-Low原型站探测波拉脉冲星附近的磁离子微结构 显示英文标题

标题： Probing magneto-ionic microstructure towards the Vela pulsar using a prototype SKA-Low station

摘要： 维拉脉冲星（J0835-4510）由于视线穿过周围的维拉超新星遗迹和古姆星云而表现出多十年尺度上的法拉第旋转和色散变化。直到现在，针对维拉的法拉第旋转变化还没有在不到大约十年的时间尺度上进行过研究。我们介绍了使用孔径阵列验证系统2（AAVS2）——一个原型SKA-Low站——进行的高频率观测活动的结果，该系统在2022年进行了显著的带宽升级。我们收集了维拉脉冲星和PSR J0630-2834（一个位于古姆星云外附近的脉冲星）的观测数据，分别覆盖了$\sim 1\,\mathrm{yr}$和$\sim 0.3\,\mathrm{yr}$，并搜索了随时间变化的旋转量（RM）中的线性趋势。在这段时间尺度（$\sim$个月）内，我们没有检测到这两个脉冲星有显著的趋势，但更准确的电离层模型可以极大地改善这些限制。对于维拉脉冲星，结合我们的数据与发表文献中的历史数据，使我们能够对过去二十年内的RM和色散量（DM）长期相关趋势进行建模。我们检测到DM的变化为$\sim 0.3\,\mathrm{cm}^{-3}\,\mathrm{pc}$，这对应于电子密度的变化为$\sim 10^5\,\mathrm{cm}^{-3}$，在横向长度尺度为$\sim$1-2个天文单位的情况下。 数据集的时间跨度内，时间变化区域中的表观磁场强度从$240^{+30}_{-20}\,\mu\mathrm{G}$变化到$-6.2^{+0.7}_{-0.9}\,\mu\mathrm{G}$。这项工作不仅为偏振测量提供了重要的验证，还突显了 SKA-Low 站点的脉冲星监测能力以及它们在高精度偏振测量和探测磁化星际介质微观结构方面的特色科学机会。 显示英文摘要

摘要： The Vela pulsar (J0835-4510) is known to exhibit variations in Faraday rotation and dispersion on multi-decade timescales due to the changing sightline through the surrounding Vela supernova remnant and the Gum Nebula. Until now, variations in Faraday rotation towards Vela have not been studied on timescales less than around a decade. We present the results of a high-cadence observing campaign carried out with the Aperture Array Verification System 2 (AAVS2), a prototype SKA-Low station, which received a significant bandwidth upgrade in 2022. We collected observations of the Vela pulsar and PSR J0630-2834 (a nearby pulsar located outside the Gum Nebula), spanning $\sim 1\,\mathrm{yr}$ and $\sim 0.3\,\mathrm{yr}$ respectively, and searched for linear trends in the rotation measure (RM) as a function of time. We do not detect any significant trends on this timescale ($\sim$months) for either pulsar, but the constraints could be greatly improved with more accurate ionospheric models. For the Vela pulsar, the combination of our data and historical data from the published literature have enabled us to model long-term correlated trends in RM and dispersion measure (DM) over the past two decades. We detect a change in DM of $\sim 0.3\,\mathrm{cm}^{-3}\,\mathrm{pc}$ which corresponds to a change in electron density of $\sim 10^5\,\mathrm{cm}^{-3}$ on a transverse length scale of $\sim$1-2 au. The apparent magnetic field strength in the time-varying region changes from $240^{+30}_{-20}\,\mu\mathrm{G}$ to $-6.2^{+0.7}_{-0.9}\,\mu\mathrm{G}$ over the time span of the data set. As well as providing an important validation of polarimetry, this work highlights the pulsar monitoring capabilities of SKA-Low stations, and the niche science opportunities they offer for high-precision polarimetry and probing the microstructure of the magneto-ionic interstellar medium.