AAS Nova Research Highlight: A Unified Explanation for Fast Radio Bursts

Professor Bing Zhang (The University of Hong Kong; The Hong Kong Institute for Astronomy and Astrophysics), in collaboration with Rui-Chong Hu (University of Nevada), has recently published a first-author paper in The Astrophysical Journal Letters proposing a unified framework to explain fast radio bursts (FRBs) with magnetars. This work has been selected by AAS Nova as one of its research highlights.

FRBs are extremely luminous radio flashes lasting from fractions of a millisecond to a few seconds. Some are seen only once, while others repeat, sometimes regularly and sometimes irregularly, posing major challenges to theoretical models. The discovery in 2020 of a FRB associated with a Galactic magnetar demonstrated that at least some FRBs originate from these highly magnetized neutron stars, but whether all FRBs could be powered by magnetars has remained an open question.

Zhang and Hu systematically examined how magnetars form — whether as isolated remnants of massive stars, products of disrupted binaries, or components of surviving binary systems — and what spin and magnetic properties they are expected to have in each channel. Their analysis indicates that most magnetars are likely isolated, in agreement with observations in the Milky Way, while a smaller fraction reside in binary systems, typically with massive stellar companions.

In their model, rapidly spinning, strongly magnetized magnetars whose spin and magnetic axes are initially well aligned can power “active” repeating FRBs. This configuration is easier to maintain in binary systems where the magnetar accretes material from the stellar wind of its companion, providing a long-lived engine for repeated bursts. Isolated magnetars, or magnetars whose axes become misaligned over time, are more naturally associated with one-off or infrequently repeating FRBs. The interaction with a companion’s wind can also account for some observed polarization properties in repeating FRBs.

While this framework shows that magnetars could in principle explain the full diversity of FRB phenomenology, the authors emphasize that other progenitor channels are not ruled out. Further multiwavelength and multimessenger observations will be essential to test and refine the magnetar scenario.