Parkes observations for project P1211 semester 2023OCTS_02

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 (e.g., pulsars in Galactic Centre and Galactic Plane). 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 EMU 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. \n \n In this proposal, we propose to observe 16 MSP candidates identified in the Galactic plane using new ASKAP EMU images. We found 23 candidates by selecting sources with spectral index steeper than -1.90 and compactness less than 1.2. Among them 7 are known pulsars giving us high fraction of pulsars (~33%) and a reasonable number of candidates to follow up (16 sources). 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于致密双星系统（如脉冲星-黑洞双星系统）中的毫秒脉冲星（millisecond pulsars, MSPs）、超快旋转脉冲星（如亚毫秒脉冲星）以及高色散量（dispersion measure, DM）脉冲星（如银心和银道面中的脉冲星）这类极端脉冲星的灵敏度不足。如今，随着澳大利亚平方千米阵探路者（Australian Square Kilometer Array Pathfinder, ASKAP）这类下一代射电望远镜阵列的发展，这一局面得以改变。ASKAP具备开展高灵敏度射电连续谱巡天的能力，可实现宽视场覆盖（例如宇宙演化巡天（Evolutionary Map of The Universe, EMU））。其中一种解决方案是在射电连续谱巡天（如EMU巡天）中搜寻脉冲星候选体，随后开展靶向搜寻。该技术能够利用全视场覆盖较宽的带宽进行搜寻，同时无需进行成本高昂的逐像素高时间分辨率搜寻。

在本提案中，我们提出利用ASKAP获取的全新EMU图像，对银道面中已识别出的16个毫秒脉冲星候选体开展观测。我们通过筛选谱指数陡于-1.90且紧凑度小于1.2的源，共找到23个候选体，其中7个为已知脉冲星，脉冲星占比约33%，同时剩余16个候选体的数量也适合开展后续跟进研究。由于银道面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遗漏了这类毫秒脉冲星。为此，我们提出利用帕克斯UWL（Parkes UWL）开展靶向脉冲星搜寻，该设备能够在更高频段搜索脉冲信号，从而规避严重的色散展宽和散射效应。