Parkes observations for project P1211 semester 2024APRS_09

Traditional pulsar searching techniques are not sensitive enough to extreme pulsars such as millisecond pulsars (MSPs) in compact binaries (e.g., Pulsar-Blackhole binary systems), extremely fast spinning pulsars (e.g., sub-MSPs), and high dispersion measure (DM) pulsars. Such a situation is now changed thanks to the development of next generation radio telescope arrays such as Australian Square Kilometer Array Pathfinder (ASKAP). ASKAP is capable of conducting highly sensitive radio continuum surveys with wide sky coverage (e.g, Evolutionary Map of The Universe survey). One of the solutions is to find pulsar candidates in radio continuum surveys such as ASKAP surveys and then carry out targeted searches. This technique allows us to search over the wide bandwidth with full field of view while avoiding the need for expensive pixel-by-pixel high time resolution searches. In this proposal, we propose to observe 16 pulsar candidates identified in the Galactic plane using new ASKAP EMU images. We found 22 candidates by selecting sources with spectral index steeper than -2.0 and compactness less than 1.2. Among them 13 are known pulsars and a reasonable number of candidates to follow up (9 sources). In total, we have 16 candidates including seven sources from 2023APRS semester. Because of the dense ionised medium in the Galactic Plane, MSPs are likely to be missed by previous pulsar surveys carried out at 1.4 GHz. Here, we propose a targeted pulsar search with the Parkes UWL which allow us to search pulsation at higher frequencies and therefore avoid strong DM smearing and scattering effects.传统脉冲星搜寻技术对极端脉冲星的探测灵敏度不足，这类极端脉冲星包括致密双星系统中的毫秒脉冲星（millisecond pulsars, MSPs，例如脉冲星-黑洞双星系统）、极快自转脉冲星（如亚毫秒脉冲星）以及高色散量（dispersion measure, DM）脉冲星。如今，随着澳大利亚平方千米阵列探路者（Australian Square Kilometer Array Pathfinder, ASKAP）等新一代射电望远镜阵列的发展，这一困境已得到改观。ASKAP可开展兼具高灵敏度与宽广天区覆盖范围的射电连续谱巡天，例如宇宙演化地图巡天（Evolutionary Map of The Universe survey，简称EMU）。 其中一种可行解决方案是在ASKAP巡天这类射电连续谱巡天中搜寻脉冲星候选体，随后开展针对性搜寻。该技术可在全视场宽带宽范围内完成搜寻，同时无需开展成本高昂的逐像素高时间分辨率搜寻工作。在本科研提案中，我们计划利用ASKAP获取的全新EMU巡天图像，对银道面中已识别出的16颗脉冲星候选体开展观测。我们通过筛选谱指数陡于-2.0且紧密度小于1.2的天体，共找到22颗脉冲星候选体。其中13颗为已知脉冲星，另有9颗具备较高后续观测价值。本次候选体总数共计16颗，其中7颗来自2023年APRS学期项目。 由于银道面中存在稠密的电离介质，此前在1.4 GHz频段开展的脉冲星巡天很可能会遗漏MSPs。在此背景下，我们计划利用帕克斯UWL开展针对性脉冲星搜寻，该设备可在更高频段搜寻脉冲脉动信号，从而规避严重的色散展宽与散射效应。