利用Parkes望远镜超宽带低频接收机搜寻SGR 1935+2154的射电脉冲

Searching for radio pulsation from SGR 1935+2154 with the Parkes ultra-wideband low receiver

在快速射电暴(FRB)被发现后不久磁陀星就被提出是可能的起源.从SGR 1935+2154中探测到的第一个河内快速射电暴FRB 200428,使得这一设想更令人信服.在2020年10月,这个源再次进入活跃状态.我们使用Parkes 64 m射电望远镜的新型超宽带低频段(UWL)接收机,对SGR 1935+2154进行了1.6 h的后随观测,频率范围为704-4032 MHz.在我们的单脉冲和周期性搜索中没有搜寻到令人信服的信号.我们使用完整的3.3 GHz带宽数据集获得的周期信号通量密度限制为3.6μJy,这是对SGR 1935+2154最严格的限制.我们对单脉冲通量的全带宽限制为35 mJyms,低于FAST射电望远镜在我们观测的两天前探测到的最亮的单脉冲.假设SGR 1935+2154在观察过程中是活跃的,我们的结果表明,它的射电暴发要么是窄带的,要么呈现较陡的频谱.

Magnetars have been proposed to be the origin of the fast radio bursts(FRBs)soon after its initial discovery.The detection of the first Galactic FRB 200428 from SGR 1935+2154 has made this hypothesis more convincing.In October 2020,this source was supposed to be in an extremely active state again.We then carried out a 1.6-hours follow-up observation of SGR 1935+2154 using the new ultra-wideband low(UWL)receiver of the Parkes 64 m radio telescope covering a frequency range of 704-4032 MHz.However,no convincing signal was detected in either of our single pulse or periodicity searches.We obtained a limit on the flux density of periodic signal of 3.6μJy using the full 3.3 GHz bandwidth data sets,which is the strictest limit for that of SGR 1935+2154.Our full bandwidth limit on the single pulses fluence is 35 mJy ms,which is well below the brightest single pulses detected by the FAST radio telescope just two days before our observation.Assuming that SGR 1935+2154 is active during our observation,our results suggest that its radio bursts are either intrinsically narrow-band or show a steep spectrum.