Newswise — Quick Radio Bursts (QRBs) represent the most luminous cosmic blasts lasting for a millisecond in the radio spectrum. Their enigmatic genesis creates hurdles for both the fields of astronomy and physics.
CRAFTS, an important initiative of the Five-hundred-meter Spherical radio Telescope (FAST) focused on Commensal Radio Astronomy, has identified the first-ever persistently active repeating FRB called FRB 20190520B. This discovery offers crucial insights that could potentially unravel the mysterious source of FRBs.
Under the leadership of Dr. LI Di from the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC), a group of international researchers conducted a monitoring survey of FRB 20190520B using both the Parkes telescope in Australia and the Green Bank Telescope (GBT) in the United States. Their joint analysis disclosed a remarkable reversal of the magnetic field around this consistently active FRB.
The findings of this research, which involved observational endeavors across three continents, were published in the journal Science on May 11th.
FRB 20190520B stands apart from all other FRBs because it emits bursts that can be detected by at least one, and sometimes multiple, telescopes consistently every time it is observed. This unprecedented level of reliability makes it a prime candidate for multiband follow-up observational studies.
Dr. DAI Shi, the principal investigator of the FRB 20190520B project at Parkes, stated that a remarkable total of 113 bursts were detected from FRB 20190520B by the Parkes telescope, which surpasses the combined number of fast radio bursts detected at Parkes before this discovery. This highlights the exceptional scientific significance of FRB 20190520B.
Using a collaborative approach that involved analyzing data from both the GBT and Parkes telescopes, Dr. FENG Yi, an NAOC PhD graduate who is currently affiliated with Zhejiang Laboratory, and Ms. Anna-Thomas from West Virginia University (WVU) investigated the polarization properties of FRB 20190520B. Their research revealed that the Faraday rotation measure (RM) of this FRB exhibited two dramatic changes in sign: from approximately 10,000 units to approximately -10,000 units and then back again. Other significant contributors to this study include Dr. Liam Connor from Caltech and Dr. Sarah Burke-Spolaor from WVU.
As burst signals propagate, the polarization properties may be influenced by the surrounding plasma. According to Dr. LI Di, the corresponding author of the study, the Faraday rotation measure (RM) is the product of the integral magnetic field and electron density, and variations in RM can be attributed to changes in either factor. However, a change in sign can only be the result of a magnetic field reversal since electron density cannot become negative.
"The inversion may arise due to transmission through a chaotic, magnetized medium of plasma situated between 10-5 to 100 parsecs from the FRB origin. As per the research co-authored by Prof. YANG Yuanpei from Yunnan University, the disorderly segments of the magnetic field surrounding recurrent quick radio bursts could be as tangled as a skein of yarn."
The probable sequence of events leading to the creation of such a disarray involves the transmission of the signal through the corona of a partner, whether it be a colossal star with gusts or a black hole. Grasping the dramatic fluctuations in the magnetized surroundings encircling the FRB is a crucial stride in comprehending the source of such astronomical outbursts.
RSS