Parkes observations for project P1131 semester 2021OCTS_09

Fast Radio Bursts (FRBs) are extragalactic radio transients with the duration time in the range of several microseconds to tens of milliseconds. The origin of them is still unclear. Ultraluminous X-ray Sources (ULXs) are objects that mostly discovered in external galaxies which host black holes or neutron stars, with isotropic luminosities exceeding the usual Eddington value for stellar-mass black holes. The host galaxies of ULXs, and their spatial offsets within their hosts, show broad similarities to those of FRB. Periodicity of days to years of some repeated FRBs could be attributed to the companion effect of ULXs. Moreover, pulsing ULXs (PULXs) which hots neutron stars may be the manifestation of accreting magnetars. Therefore, we propose targeted FRB searches of known PULXs, which have not yet been carried out by other telescopes according to published literature to date. Our observations will play an important role in investigating the FRB progenitors. If FRBs were detected in our selected ULXs, then puzzle of FRBs' origin would be directly resolved. If no FRB is detected, we can still constrain some ULX-related models statistically, e.g. the upper limit of the burst rate, the period of duty cycle, etc. Our observations can also be used to hunt for radio pulsars in PULXs.

快速射电暴（Fast Radio Bursts，FRBs）是一类河外射电暂现源，持续时长介于数微秒至数十毫秒之间，其起源至今仍未明晰。超亮X射线源（Ultraluminous X-ray Sources，ULXs）多发现于携带有黑洞或中子星的河外星系，其各向同性光度远超恒星质量黑洞的标准爱丁顿极限。超亮X射线源的宿主星系及其在宿主星系内的空间偏移特征，与快速射电暴的对应特征存在广泛相似性。部分重复快速射电暴所呈现的日至年尺度周期性，可归因于超亮X射线源的伴星效应。此外，承载中子星的脉冲式超亮X射线源（Pulsing Ultraluminous X-ray Sources，PULXs），可能是吸积磁星的观测表现形式。因此，我们提议对已知的脉冲式超亮X射线源开展定向快速射电暴搜寻——截至目前，已发表的文献显示尚无其他望远镜开展过此类观测。本观测项目将为快速射电暴起源天体的研究发挥关键作用。若在我们选定的超亮X射线源中探测到快速射电暴，将直接解开快速射电暴的起源之谜；若未探测到快速射电暴，我们仍可通过统计分析约束若干与超亮X射线源相关的理论模型，例如暴发率上限、占空比周期等。本观测项目还可用于搜寻脉冲式超亮X射线源中的射电脉冲星。