Parkes observations for project P1150 semester 2022APRS_04

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.

迄今，已确认的河外射电脉冲星仅存在于麦哲伦云星系中，其中大麦哲伦星系（Large Magellanic Cloud，LMC）的脉冲星发现数量更为丰富。然而，截至目前，无论是大麦哲伦星系还是银河系外的其他区域，均未发现毫秒脉冲星（millisecond pulsars，MSPs）。由于绝大多数毫秒脉冲星均处于双星系统之中，对其进行发现与研究，将有助于我们理解大麦哲伦星系内双星脉冲星的演化历程、毫秒脉冲星的伴星特性，以及大麦哲伦星系独特的恒星形成环境。我们在一项针对大麦哲伦星系的高分辨率多波束巡天观测中，发现了一批强度较弱但极具潜力的毫秒脉冲星候选体。尽管这些候选体的特征显示其可能为真实脉冲星，但巡天数据中的探测信号强度过低，无法仅凭此确定性地验证其真伪。因此需要开展后续验证工作，而UWL接收机可使此类验证成为可能。我们估算，相较于多波束系统，UWL接收机的灵敏度更高，因此可通过对每个候选体进行1小时的积分观测，获得信噪比（Signal-to-Noise Ratio，S/N）大于10~12的清晰验证探测结果。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，申请总时长共计10小时（含设备设置与天线指向切换的额外开销时间）。若这些候选体得以验证，它们将成为人类有史以来发现的首批河外射电毫秒脉冲星。