利用默奇森大视场阵列旁瓣探寻北天脉冲星

Search and detection of northern pulsars in the side lobes of the murchison wide-field array

探索新的方法对发现和观测脉冲星具有重要意义.本文利用澳大利亚的默奇森大视场阵列望远镜MWA(Murchison Wide-field Array)中心频率185 MHz的观测数据进行脉冲星搜寻,探测到了两颗高纬度北天脉冲星,经分析认定为J0332+5434和J2219+4754.它们位于MWA主波束视场以外赤纬30°以北,而落在MWA非相干波束的北天旁瓣.虽然射电望远镜旁瓣的灵敏度远低于主瓣,但大多数脉冲星的低频流量更高,因而仍然可以利用低频望远镜旁瓣对它们进行搜寻与观测.本文将对低频脉冲星的搜索流程和结果进行阐述,并讨论利用MWA射电望远镜旁瓣进一步搜寻和观测北天脉冲星的可能性.通过对已知射电脉冲星的统计和MWA探测灵敏度的模拟,预计有30颗已知北天脉冲星可以在MWA旁瓣中被探测到.此工作是未来使用SKA低频阵列搜寻北天脉冲星的有益探索.

New pulsar searching methods can significantly enhance the discovery of new pulsars and observations of single pulsars.This paper searches for pulsars among the observations centered at 185 MHz collected by the Murchison Wide-field Array(MWA).The declinations of two high-latitude northern sky pulsars,identified as J0332+5434 and J2219+4754,exceeded the commonly considered detection limit of MWA(declination≤30°),and appeared in the side lobes of MWA’s incoherent beams.Although the sensitivity is substantially lower in the side lobes than in the main lobe,pulsars are generally very bright at low frequencies,so are observable in the side lobes of low-frequency,wide field of view telescopes.This article describes the search for pulsars with the MWA,and discusses the possibility of further searching and observing the northern sky pulsars in the MWA side lobes.In a simulation study,the MWA detection sensitivity was evaluated at several flux densities of known radio pulsars.We estimated that approximately 30 known northern sky pulsars can be detected in the MWA side lobes.This work promises future pulsar searching by the Square Kilometer Array at low frequencies.