Researchers discover twisting fields around a mysterious fast radio burst

Fast radio bursts (FRBs) are the brightest millisecond cosmic explosions in the radio bands. Their unknown origin poses challenges for astronomy as well as physics.

The Collaborative Radio Astronomy Rapid Survey (CRAFTS), a flagship program of the Five Hundred Meter Aperture Spherical Radio Telescope (FAST), has detected the world’s first continuously active FRB, known as FRB 20190520B. Now the FRB has provided clues that may help clarify the origin of FRBs.

An international team led by Dr Li Di of the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC) has conducted a campaign to observe FRB 20190520B, using the Parkes Telescope in Australia and the Green Bank Telescope (GBT) in the United States. Pooled analyzes revealed intense field reversal around this continuously explosive source.

The study, which is based on monitoring efforts across three continents, was published in Sciences On May 11th.

Unlike all other FRBs, FRB 20190520B produced bursts, detectable by at least one and sometimes multiple telescopes, each time it was viewed. This reliability makes it an ideal target for multiscale follow-up observational studies.

“A total of 113 bursts of FRB 20190520B were detected by the Parkes telescope, which exceeds the total number of fast radio bursts previously detected at Parkes, highlighting the value of FRB 20190520B,” said Dr Dai Shi of Western Sydney University, PI. From Project FRB 20190520B at Parkes.

Through a joint analysis of data from GBT and Parkes, Dr. Feng Yi obtained his Ph.D. from NAOC. Now a graduate of the Zhejiang Laboratory, Ms. Reshma Anna Thomas of West Virginia University (WVU) measured the polarization properties and found that the Faraday rotation scale (RM) changed its sign twice in a dramatic way: from ~10,000 units to ~10,000 units. units and vice versa. Other major contributors include Dr. Liam Connor of Caltech and Dr. Sarah Burke Spollor of WVU.

During propagation of the burst signal, the polarization properties of the surrounding plasma can be affected. RM can be approximated by the integral product of the magnetic field and electron density. Dr Li Di, corresponding author of the study, said the variance in RM could be caused by either factor, but the sign change must arise from reversal of magnetic fields, because the electron density cannot become negative.

This reflection could result from propagation through a turbulent magnetic screen of plasma located between 10^-5 to 100 parsecs from the FRB source. Turbulent components of the magnetic field around repetition Fast radio blasts It might be as messy as a ball of wool,” said Professor Yang Yuanpei of Yunnan University, co-author of the study.

A possible scenario for producing such chaos includes the signal passing through the halo of a companion, whether that be a black hole or a massive star with winds. Understanding the drastic changes in the magnetization environment around the FRB is an important step towards understanding the origin of such cosmic explosions.