Fast radio bursts (FRBs) are millisecond-long cosmic explosions, each producing an energy equivalent to the Sun’s annual output. More than 15 years after deep-space pulses of electromagnetic radio waves were first discovered, their puzzling nature continues to surprise scientists — and newly published research only deepens the mystery surrounding them.
In the September 21 issue natureUnexpected new observations of a series of cosmic fast radio bursts by an international team of scientists including UNLV astrophysicist Bing Zhang challenge common understandings of FRB physics and the central engine.
Cosmic FRB observations were made in late spring 2021 using China’s Large 500-meter Aperture Spherical Radio Telescope (FAST). The research team, led by Xu Heng, Li Kejia, Dong Subo of Peking University, and Zhu Weiwei of China’s National Astronomical Observatory, detected 1,863 outbursts of 20201124A from an active fast radio burst source called FRB in 82 hours over 54 days.
“This is the largest sample of FRB data with polarization information from a single source,” Lee said.
Recent observations of a FRB from our galaxy suggest that it originated from a magnetar, a dense, city-sized neutron star with an incredibly strong magnetic field. On the other hand, the origin of very distant cosmic FRBs remains unknown. The latest observations have scientists questioning how much they think they know about them.
“These observations put us back on the drawing board,” said Zhang, who is also founding director of UNLV’s Nevada Center for Astrophysics. “It is clear that FRBs are more mysterious than we thought. More multi-wavelength observational campaigns are needed to further reveal the nature of these objects.”
The latest observation that surprised the scientists was an irregular, short-time variation in so-called “Faraday rotation measurements,” which are the magnetic field strength and particle density near the FRB source. Changes fluctuated up and down during the first 36 days of observation and stopped abruptly during the last 18 days before the source went out.
“I equate it with taking a film of the environment around the FRB source, and our film reveals a complex, dynamically evolving, magnetized environment that was never imagined before,” Zhang said. “This environment is not directly expected for an isolated magnetar. There may be something else near the FRB engine, possibly a binary companion,” Zhang added.
To observe the FRB’s host galaxy, the team also utilized the 10-meter Keck Telescope on Mauna Kea, Hawaii. Young magnetars are thought to exist in active star-forming regions of star-forming galaxies, Zhang said, but optical images of the host galaxy showed—unexpectedly—that the host galaxy is a metal-rich barred spiral galaxy like The same is true for our Milky Way. The FRB is located in a region with no apparent star formation activity.
“This location is inconsistent with the central motor of young magnetars formed during extreme explosions, such as long gamma-ray bursts or superluminous supernovae, and is widely speculated to be a precursor to active FRB motors,” Dong said.
Research published September 21 in the journal “Fast radio burst sources at complex magnetization sites in barred galaxies” nature Includes 74 co-authors from 30 institutions. In addition to UNLV, Peking University, and the National Astronomical Observatory of China, cooperative institutions include Purple Mountain Observatory, Yunnan University, University of California, Berkeley, Caltech, Princeton University, University of Hawaii, China, the United States, Australia, Germany, and Israel.
Astronomers find clues that unravel the mystery of fast radio bursts
H. Xu et al., FRB sources at complex magnetization sites in barred galaxies, nature (2022). DOI: 10.1038/s41586-022-05071-8
Courtesy of University of Nevada, Las Vegas
Citation: Astronomers reveal puzzling new signature of mysterious fast radio burst (September 22, 2022), accessed September 23, 2022 from https://phys.org/news/2022-09- astronomers-unveil-newand-puzzlingfeatures-mysterious.html retrieved
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