Twisted magnetic fields engulf a mysterious cosmic signal

May 12. (EUROPE PRESS) –

Combined monitoring and analysis of a mysterious FRB cosmic radio signal have revealed an extreme reversal of the magnetic field around this constantly bursting fountain.

Fast Radio Bursts (FRBs) are the brightest millisecond-long cosmic explosions in radio bands. Its unknown origin poses challenges for both astronomy and physics. The new research is published in Science.

The Commensal Radio Astronomy FAST Survey (CRAFTS), a key program of China’s Five Hundred Meter Spherical Radio Telescope (FAST), discovered the world’s first persistently active repeating FRB, known as FRB 20190520B. Now, in a study carried out with the Parkes (Australia) and Green Bank (USA) observatories, this FRB has provided clues that may help clarify the origin of those signals.

Unlike all other FRBs, FRB 20190520B has produced outbursts, detectable by at least one and sometimes multiple telescopes, every time it has been observed. This reliability makes it an ideal target for multiband follow-up observational studies.

“A total of 113 outbursts from FRB 20190520B were detected by the Parkes telescope, exceeding the sum of the number of fast radio outbursts previously discovered in Parkes, accentuating the value of FRB 20190520B,” he explains. it’s a statement Dr. DAI Shi from the University of Western Sydney, Principal Investigator of the FRB 20190520B project in Parkes.

Through a combined analysis of the GBT and Parkes data, Dr. FENG Yi, an NAOC PhD graduate now in the Zhejiang Laboratory, and Anna-Thomas of West Virginia University (WVU) measured its polarization properties. and found that the Faraday rotation (RM) measure changed its sign dramatically twice: from about 10,000 units to about 10,000 units and vice versa.

During the propagation of a burst signal, the polarization characteristics can be affected by the surrounding plasma. “MR can be approximated by the integral product of the magnetic field and the electron density. The MR variation can be due to either of the two factors, but the sign change has to arise from the reversal of the magnetic fields, since the electron density cannot become negative,” explains Dr LI Di in a statement. , corresponding author of the study.

This reversal could be due to propagation through a turbulent, magnetized plasma screen located between 10-5 and 100 parsecs from the FRB source. “The turbulent components of the magnetic field around repeated fast radio bursts they can be as messy as a ball of yarn“, says Professor YANG Yuanpei, from the University of Yunnan, a co-author of the study.

The signal is most likely passing through the halo of a companion, either a black hole or a massive star with winds. Understand drastic changes in the magnetized environment surrounding the FRB is an important step to understand the origin of such cosmic explosions, the researchers conclude.