近日，澳大利亚科廷大学的N.Hurley-Walker及其研究小组取得一项新进展。经过不懈努力，他们发现了活跃了三十年的长周期射电暂现源。相关研究成果已于2023年7月19日在国际权威学术期刊《自然》上发表。

该研究团队报道了名为GPM J1839-10的长周期射电暂现源的观测结果，其周期为21分钟。研究人员发现脉冲的亮度变化跨越了两个数量级，持续时间在30到300秒之间，并具有准周期性的子结构。这些观测结果促使研究人员对射电档案进行了搜索，结果发现至少从1988年开始，这个源一直在重复。通过档案数据，周期导数被限制在3.6×10^-13 ss^-1，这超过了任何预测孤立中子星偶极射电发射的经典理论模型的极限。

据悉，人们最近发现了几个长周期的射电暂现源，这些源在在几十到几千秒的时间尺度上出现了强极化的相干射电脉冲。在某些情况下，这些射电脉冲被解释为来自具有极强磁场的旋转中子星，即磁星；而其他偶尔周期性且采样较少的射电暂现源的起源仍在争论中。通常，相干周期性射电发射被解释为由旋转的偶极磁场和对偶产生机制造成，然而，这种模型不易预测这些缓慢旋转的中子星的射电发射并维持较长时间。另一方面，虽然高磁场孤立的白矮星预计具有较长的自旋周期，但尚未直接从这些源中检测到周期性的相干射电发射。

附：英文原文

Title: A long-period radio transient active for three decades

Author: Hurley-Walker, N., Rea, N., McSweeney, S. J., Meyers, B. W., Lenc, E., Heywood, I., Hyman, S. D., Men, Y. P., Clarke, T. E., Coti Zelati, F., Price, D. C., Horvth, C., Galvin, T. J., Anderson, G. E., Bahramian, A., Barr, E. D., Bhat, N. D. R., Caleb, M., DallOra, M., de Martino, D., Giacintucci, S., Morgan, J. S., Rajwade, K. M., Stappers, B., Williams, A.

Issue&Volume: 2023-07-19

Abstract: Several long-period radio transients have recently been discovered, with strongly polarized coherent radio pulses appearing on timescales between tens to thousands of seconds. In some cases, the radio pulses have been interpreted as coming from rotating neutron stars with extremely strong magnetic fields, known as magnetars; the origin of other, occasionally periodic and less-well-sampled radio transients is still debated. Coherent periodic radio emission is usually explained by rotating dipolar magnetic fields and pair-production mechanisms, but such models do not easily predict radio emission from such slowly rotating neutron stars and maintain it for extended times. On the other hand, highly magnetic isolated white dwarfs would be expected to have long spin periodicities, but periodic coherent radio emission has not yet been directly detected from these sources. Here we report observations of a long-period (21min) radio transient, which we have labelled GPM J1839–10. The pulses vary in brightness by two orders of magnitude, last between 30 and 300s and have quasiperiodic substructure. The observations prompted a search of radio archives and we found that the source has been repeating since at least 1988. The archival data enabled constraint of the period derivative to <3.6×10^-13ss^-1, which is at the very limit of any classical theoretical model that predicts dipolar radio emission from an isolated neutron star.

DOI: 10.1038/s41586-023-06202-5

Source: https://www.nature.com/articles/s41586-023-06202-5