Parkes observations for project P1131 semester 2021OCTS_03

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）是一类持续时长为数微秒至数十毫秒的河外射电瞬变源，其起源至今仍未明确。超亮X射线源（Ultraluminous X-ray Sources, ULXs）是一类多发现于寄主星系存在黑洞或中子星的河外星系中的天体，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射线源的寄主星系及其在寄主星系内的空间偏移量，与快速射电暴的相关特征存在广泛相似性。部分重复快速射电暴呈现的数天至数年的周期性，可归因于超亮X射线源的伴星效应。此外，寄主为中子星的脉冲式超亮X射线源（pulsing ULXs, 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射线源开展针对性的快速射电暴搜寻——截至目前，根据已发表的学术文献，其他望远镜尚未开展此类观测。本观测计划将为快速射电暴的起源前身天体研究发挥关键作用。若在我们选定的超亮X射线源中探测到快速射电暴，则可直接解决快速射电暴起源的核心谜题；若未探测到快速射电暴，我们仍可通过统计分析约束部分与超亮X射线源相关的理论模型，例如暴率上限、占空比周期等。本观测计划还可用于搜寻脉冲式超亮X射线源中的射电脉冲星。