Parkes observations for project P1295 semester 2023OCTS_06

We propose observing time with the Parkes telescope to investigate four ``spider" millisecond pulsars (MSPs), PSR J1048+2339 (a redback spider), PSR J1908+2105 (an MSP that occupies a region of parameter space between black widows and redbacks), PSR J2052+1219 and PSR J2256-1024 (black widow spiders). Spider MSPs are commonly seen to exhibit frequency-dependent eclipsing. Observations with wide bandwidth telescopes like Parkes UWL (700-4000 MHz) will be extremely useful to study the eclipse mechanisms in these systems. Eclipse properties of spider MSPs are hitherto unexplored at the frequency regime available with the Parkes UWL receiver. We propose to investigate a sample of 4 MSPs mentioned above (for which polarization has not been studied) with the Parkes telescope using the UWL receiver in full polar mode, which will be addressed with this proposal. One of the aims is to model the eclipse phase spectra using wideband observations of these pulsars in an optically thick-to-thin transitioning regime (optical depth nearly 1), to explore the eclipse mechanism.\n Observing the possible changes in rotation measure (RM) at eclipse ingress and egress will allow us to probe the magnetic field in the eclipse boundaries. \n We request to cover nearly one full orbit for each of these MSPs. Thus we propose 23 hours of observing time including time for setup and calibration in each epoch with the Parkes UWL receiver for the investigation of the eclipse mechanism as well as the polarization, profile evolution, and spectra of four spider MSPs.

本研究提议申请帕克斯望远镜（Parkes Telescope）观测时长，以研究4颗“蜘蛛类”毫秒脉冲星（millisecond pulsar, MSP）：PSR J1048+2339（红背蜘蛛型）、PSR J1908+2105（参数空间处于黑寡妇与红背蜘蛛型之间的MSP）、PSR J2052+1219与PSR J2256-1024（黑寡妇蜘蛛型）。
蜘蛛类MSP普遍表现出频率依赖性食现象。诸如帕克斯UWL接收机（Parkes UWL Receiver，工作频段700-4000 MHz）这类宽频带望远镜的观测数据，将为探究此类系统的食变机制提供关键支撑。截至目前，针对帕克斯UWL接收机覆盖的频段范围，蜘蛛类MSP的食特性尚未有相关研究开展。
本研究提议使用帕克斯望远镜的UWL接收机全偏振模式（full polar mode），对上述4颗尚未开展偏振研究的MSP样本开展观测，此为本次申请的核心内容之一。其中一项科学目标为：在光深（optical depth）接近1的厚-薄光学过渡区间内，通过对这些脉冲星的宽带观测构建食相光谱模型，以探究食变机制；通过观测食相进入与退出阶段的旋转测量（rotation measure, RM）变化，可探测食边界处的磁场环境。
我们申请为每颗MSP覆盖近乎完整的一个轨道周期（orbit）。因此，本次申请提议在每个观测时段（epoch）使用帕克斯UWL接收机开展总计23小时的观测，其中包含设备调试与校准时间，以研究这4颗蜘蛛类MSP的食变机制、偏振特性、轮廓演化及光谱特征。