In a combined analysis with other published data amounting to a total of 9 repeating and 12 single-burst FRBs, the researchers were able to quantitatively describe the depolarization toward low frequencies based on a simple physical picture, namely multi-path RM scattering. FENG Yi, currently a staff scientist at the Zhejiang National Lab. Later, when we systematically looked into these FRBs with other major facilities in other frequency bands, particularly those higher than that of FAST, a unified picture emerged," said the first author of the paper, Dr. "We were much puzzled by the lack of polarization in most of our observations. The team has also continued to monitor other active repeaters with FAST. LI Di, the corresponding author of both papers. "Non-detection of linear polarization is a norm rather than exception with FAST in its band between 1.0-1.4 GHz, despite its unparalleled sensitivity," said Dr. In a 50-day span in 2019, FAST detected 1,652 pulses, but no polarization has been detected within this treasure trove (Li et al. Such a unified description of repeating FRBs indicates a complex environment near and/or around the bursting sources, which could be a supernova remnant, a pulsar wind nebula, or plasma near massive blackholes.įRB 121102, the first repeating FRB source, possesses a high degree of polarization with a correspondingly extremely large RM, which is a product of electron density and magnetic field strength along the line of sight.
The study was published in Science on March 18.Ĭombined with a diverse set of existing data, these observations reveal systematic frequency evolution, namely depolarization toward lower frequencies, which can be well described by a single parameter, i.e., rotation measure (RM) scattering (σRM). LI Di from National Astronomical Observatories of Chinese Academy of Sciences (NAOC) has analyzed the polarization properties of five repeating FRB sources using the Five-hundred-meter Aperture Spherical radio Telescope (FAST) and the Robert C. High-fidelity polarization measurements of FRBs are thus crucial to understanding their origin.Ī research team led by Dr. The polarization of FRBs contains crucial information about their environments. A new unified characterization of FRB reveals their origin (Image by CAS/NAOC/ScienceApe)įast radio bursts (FRBs) are the brightest millisecond-duration astronomical transients in radio bands with yet unknown origin.
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