By analyzing the observation data of the "China Celestial Eye" (FAST), researchers from the National Astronomical Observatory of the Chinese Academy of Sciences and other institutions found that a small number of bursts of repeated rapid radio bursts have the characteristics of circularly polarized radiation, and the degree of circularly polarized radiation can reach 64%. Such a high degree of circular polarization indicates that circular polarization may result from Faraday transformation in extreme magnetic field environment, or the characteristics of fast radio burst source itself. Relevant research results were published in the Science Bulletin on December 26. Rapid Radio Burst (FRB) is the strongest burst phenomenon in the radio wave band of the universe. Its radiation mechanism and origin are unknown. Since the first rapid radio burst was discovered in 2007, more than 600 rapid radio bursts have been detected so far. As one of the basic properties of electromagnetic wave, polarization carries the radiation characteristics of the light source itself and the key information of the light propagation environment. "General light sources, including incandescent lamps and most stars such as the sun, belong to non polarized light sources. Almost all repetitive bursts of fast radio bursts have been detected to have linear polarization, but circular polarization is rare. Previously, only one repetitive burst FRB20201124A had circular polarization," said Li Di, a researcher at the National Astronomical Observatory of the Chinese Academy of Sciences. FRB20121102A is the first case of repetitive bursts found. The FRB20190520B is the first case of continuous active repetitive bursts found during the simultaneous inspection of multiple scientific objectives of the "China Tianyan". Li Di said, "As two of the hundreds of fast radio bursts with radio persistent sources (PRS), they may represent a special origin or a special stage of evolution." Through in-depth observation, China's Tianyan captured the extreme active period of these two fast radio bursts, thus accumulating a lot of valuable observation data, This enables researchers to accurately depict the polarization characteristics of this mysterious phenomenon in the dynamic universe. After analyzing the observed data of FRB20121102A and FRB20190520B, researchers found that less than 5% of the small bursts of these two repetitive bursts have circularly polarized radiation characteristics. This discovery increases the number of samples with circularly polarized repetitive bursts from 1 to 3. Li Di said that as one of the few active repetitive rapid radio bursts, the detection of circular polarization of FRB20121102A, FRB20190520B and FRB20201124A suggests that circular polarization may be a common feature of repetitive rapid radio bursts. "China's Tianyan" depicts the radio frequency polarization characteristics of the dynamic universe in detail, which will deepen the understanding of the radiation mechanism of rapid radio bursts, and is expected to eventually reveal the origin of this mysterious astrophysical phenomenon. (Liu Xinshe)