Parkes observations for project P1211 semester 2024APRS_13

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（例如脉冲星-黑洞双星系统）中的毫秒脉冲星（millisecond pulsars, MSPs）、极高速旋转脉冲星（例如亚毫秒脉冲星，sub-MSPs）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。这一现状如今已随着新一代射电望远镜阵列的发展而得到改变，例如澳大利亚平方千米阵列探路者（Australian Square Kilometer Array Pathfinder, ASKAP）。ASKAP具备开展高灵敏度射电连续谱巡天的能力，且拥有宽广的天区覆盖范围，例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巡天这类射电连续谱巡天中识别脉冲星候选体，随后开展针对性搜寻。该技术可在全视场范围内覆盖宽广带宽开展搜寻，同时无需开展代价高昂的逐像素高时间分辨率搜寻。在本提案中，我们计划对银道面中利用ASKAP全新EMU图像识别出的16个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的射电源，共找到22个候选体。其中13个为已知脉冲星，另有数量可观的待跟进候选体（共9个射电源）。总体而言，我们共纳入16个候选体，其中7个来自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会遗漏MSPs。在此背景下，我们计划利用帕克斯UWL（Parkes UWL）望远镜开展针对性脉冲星搜寻，该设备可在更高频段搜寻脉冲信号，从而规避严重的DM弥散与散射效应。