Parkes observations for project P1150 semester 2022APRS_08

To date, the only radio pulsars that have been confirmed outside of our Galaxy lie in the Magellanic Clouds, with the LMC being the richer of the two galaxies in terms of pulsar discoveries. However, no millisecond pulsars (MSPs) have yet been discovered in the LMC or anywhere outside of our Galaxy. Since the majority of MSPs reside in binary systems, the discovery and study of MSPs can help us understand LMC binary pulsar evolution and MSP companion characteristics, as well as the different star formation environment of the LMC. We have discovered a number of weak but promising MSP candidates in a survey of the LMC in a high-resolution multibeam survey. Although these candidates have characteristics that suggest they are real, the detections from the survey data are too weak by themselves to definitively state whether they are real or not. Follow-up confirmations are thus required, and the UWL receiver makes such confirmations feasible. We estimate that with the increased sensitivity of the UWL compared to the multibeam system, we can obtain clear confirmation detections with S/N > 10-12 with one-hour integrations per candidate. We propose to confirm 10 of our MSP candidates from the survey with one-hour observations with the UWL system, which totals 10 hr of time requested (plus overhead time for setup, and slew). If these candidates are confirmed, these would be the first extragalactic radio MSPs ever discovered.

截至目前，已在银河系外确认的射电脉冲星（radio pulsars）仅存在于麦哲伦云，其中大麦哲伦云（Large Magellanic Cloud，LMC）是这两个星系中脉冲星发现数量更多的一个。然而，截至目前尚未在大麦哲伦云或银河系外任何区域发现毫秒脉冲星（millisecond pulsars，MSPs）。由于绝大多数毫秒脉冲星均处于双星系统中，对其开展发现与研究，有助于我们理解大麦哲伦云内双星脉冲星的演化历程、毫秒脉冲星的伴星特性，以及大麦哲伦云独特的恒星形成环境。我们在针对大麦哲伦云的高分辨率多波束巡天中，发现了一批强度较弱但极具潜力的毫秒脉冲星候选体。尽管这些候选体具备指向其真实性的特征，但仅依靠本次巡天数据的探测信号强度不足，无法确切判定其真伪，因此需要开展后续验证工作，而UWL接收机可使这类验证成为可行方案。经估算，相较于多波束系统，UWL接收机的灵敏度更高，我们可通过对每个候选体进行1小时的积分观测，获得信噪比（S/N）大于10至12的明确验证探测结果。我们计划利用UWL系统对本次巡天发现的10个毫秒脉冲星候选体开展1小时观测以完成验证，总申请观测时长为10小时（含设备筹备及天线转场耗时）。若这些候选体得以验证，它们将成为人类首次发现的河外射电毫秒脉冲星。