Parkes observations for project P1131 semester 2021OCTS_06

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暂现源，其起源至今尚未明晰。超亮X射线源（Ultraluminous X-ray Sources, ULXs）是多数发现于河外星系的天体，这类天体通常承载黑洞或中子星，其各向同性光度超过恒星级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，与快速射电暴展现出广泛的相似性。部分重复快速射电暴呈现数日至数年的周期性，这一特性可归因于超亮X射线源的伴星效应。此外，搭载中子星的脉冲型超亮X射线源（pulsing ULXs, PULXs）或为吸积磁星的观测表征。据此，我们提出对已发现的脉冲型超亮X射线源开展定向快速射电暴搜寻——截至目前，已发表的学术文献中尚无其他望远镜开展过此类观测项目。本观测计划将为探究快速射电暴的前身天体提供关键支撑。若在选定的超亮X射线源中探测到快速射电暴，将直接破解快速射电暴的起源谜团；若未探测到信号，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，例如爆发率上限、占空比周期等。此外，本观测还可用于搜寻脉冲型超亮X射线源中的射电脉冲星。