Parkes observations for project P1211 semester 2024APRS_16

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致密双星系统中的毫秒脉冲星（millisecond pulsars, MSPs，如脉冲星-黑洞双星系统）、超高速旋转脉冲星（如亚毫秒脉冲星）以及高色散量（dispersion measure, DM）脉冲星这类极端脉冲星的探测灵敏度不足。
这一局面如今随着新一代射电望远镜阵列——例如澳大利亚平方千米阵列探路者（Australian Square Kilometer Array Pathfinder, ASKAP）——的发展得以扭转。ASKAP具备开展高灵敏度、大天区覆盖的射电连续谱巡天的能力，比如宇宙演化地图巡天（Evolutionary Map of The Universe survey, EMU）。
其中一种可行方案是在ASKAP巡天等射电连续谱巡天中筛选脉冲星候选体，随后开展针对性搜寻。该技术可在全视场宽带宽范围内开展搜寻，同时无需进行成本高昂的逐像素高时间分辨率搜索。
在本研究提案中，我们拟借助ASKAP最新发布的EMU图像，对银道面内已识别出的脉冲星候选体开展观测。我们通过筛选谱指数陡于-2.0且紧凑度小于1.2的源，共找到22颗候选体，其中13颗为已知脉冲星，另有9颗具备后续跟进研究价值的候选源。最终我们共计确定16颗候选体，其中7颗来自2023年APRS学期项目。
由于银道面中存在致密的电离介质，此前在1.4 GHz频段开展的脉冲星巡天很可能遗漏了MSPs。为此，我们计划利用Parkes UWL开展针对性脉冲星搜寻，该设备可在更高频段搜索脉冲信号，从而规避严重的DM弥散与散射效应。