Parkes observations for project P1165 semester 2023APRS_01

We carried out a pilot FAST survey at intermediate Galactic latitudes and discovered five new pulsars (including two millisecond pulsars, MSPs). We confirmed all five pulsars and timed two pulsars (J1826-0049 and J1849+1000) during the 2022OCTS semester. A coherent timing solution was obtained for J1826-0049 (4.59 ms) and it is in a 6.7-day orbit with a white dwarf companion. The other pulsar, J1849+1000, turned out to be potentially exotic. While its large spin period variation can be fitted by a 26-day circular orbit with a massive companion, the residuals show strong quasi-periodic variations, which suggest the existence of a third object in an inner orbit. If confirmed, J1849+1000 will be in a stellar triple system with an outer orbit of 26 days and an inner orbit of a few days. This makes it potentially a unique system for tests of gravitational theories and understanding the formation and evolution of triple systems. Here we propose to continue our timing of J1826-0049 and J1849+1000. The goal is to refine our measurement of the parameters of J1826-0049 and understand the nature of J1849+1000我们依托FAST（500米口径球面射电望远镜）在银河中等银纬区域开展先导巡天，共发现5颗新脉冲星，其中包含2颗毫秒脉冲星（millisecond pulsars, MSPs）。我们已完成全部5颗脉冲星的证认，并在2022年10月观测学期内对J1826-0049与J1849+1000两颗脉冲星开展了计时观测。针对J1826-0049，我们获得了相干计时解，其自转周期为4.59 ms，且该脉冲星处于一颗白矮星伴星的6.7天轨道系统中。另一颗脉冲星J1849+1000则展现出潜在的反常特性：尽管其显著的自转周期变化可通过一颗大质量伴星的26天圆轨道进行拟合，但计时残差仍呈现出强烈的准周期波动，这暗示其内层轨道中存在第三颗天体。若该推论得到证实，J1849+1000将属于一个三星系统：外层轨道周期为26天，内层轨道周期仅为数天。这使得该系统成为检验引力理论、探究三星系统形成与演化机制的独特天体物理对象。在此，我们提议继续对J1826-0049与J1849+1000开展计时观测，其目标为优化J1826-0049的参数测量精度，并阐明J1849+1000的物理本质。