Astronomers reveal new—and surprising—characteristics of mysterious fast radio bursts

Astronomers reveal new—and surprising—characteristics of mysterious fast radio bursts

Artist’s rendering of the Five Hundred Meter Aperture Spherical Radio Telescope (FAST) in China. Credit: Jingchuan Yu

Fast radio bursts (FRBs) are millisecond cosmic explosions that each produce energy equivalent to the sun’s annual output. More than 15 years after deep space electromagnetic radio wave pulses 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 of the magazine The natureunexpected new observations of a series of fast cosmic radio bursts by an international team of scientists—including UNLV astrophysicist Bing Zhang—challenge the prevailing understanding of the physical nature and central driver of FRBs.

The cosmic FRB observations were made in late spring 2021 using China’s massive Five Hundred Meter Aperture Spherical Radio Telescope (FAST). The team, led by Heng Xu, Kejia Lee, Subo Dong of Peking University and Weiwei Zhu of the National Astronomical Observatories of China, along with Zhang, detected 1,863 bursts in 82 hours over 54 days from a source active fast radio burst called FRB 20201124A.

“This is the largest sample of FRB data with polarization information from a single source,” Lee said.

Recent observations of a fast radio burst in our Milky Way galaxy suggest that it originated from a magnetar, which is a dense, city-sized neutron star with an incredibly strong magnetic field. The origin of very distant cosmological fast radio bursts, on the other hand, remains unknown. And the latest observations leave scientists questioning what they thought they knew about them.

“These observations brought us back to the drawing board,” said Zhang, who is also the founding director of UNLV’s Nevada Center for Astrophysics. “It’s clear that FRBs are more mysterious than we imagined. More multi-wavelength observing campaigns are needed to further reveal the nature of these objects.”

What makes the latest observations surprising to scientists are the erratic, short-lived variations in the so-called “Faraday rotation measure,” which is the magnetic field strength and particle density in the vicinity of the FRB source. The variations waxed and waned during the first 36 days of observation and stopped abruptly during the last 18 days before the source died out.

“I equate it to shooting a movie from the surroundings of an FRB source, and our movie revealed a complex, dynamically evolving, magnetized environment that had never been imagined before,” Zhang said. “Such an environment is not expected for an isolated magnetar. “Something else could be near the FRB engine, possibly a binary companion,” Zhang added.

To observe the FRB’s host galaxy, the team also used the 10m Keck telescopes located at Mauna Kea in Hawaii. Young magnetars are thought to reside in the active star-forming regions of a star-forming galaxy, but the optical image of the host galaxy unexpectedly shows that the host galaxy is a metal-rich barred spiral galaxy like the Way Dairy. . The location of the FRB is in a region where there is no significant star formation activity.

“This location is inconsistent with a young central magnetar engine formed during an extreme outburst, such as a long gamma-ray burst or a superluminous supernova, widely speculated progenitors of active FRB engines,” Dong said.

The study, “A fast radio burst source at a complex magnetized site in a bard galaxy,” appeared Sept. 21 in the journal. The nature and includes 74 co-authors from 30 institutions. In addition to UNLV, Peking University, and the National Astronomical Observatories of China, collaborating institutions also include the Purple Mountain Observatory, Yunnan University, UC Berkeley, Caltech, Princeton University, the University of Hawaii, and other institutions in China, the US, Australia, Germany, and Israel.

Astronomers discover clues that unravel the mystery of fast radio bursts

More information:
H. Xu et al., A fast radio burst source at a complex magnetized site in a barred galaxy, The nature (2022). DOI: 10.1038/s41586-022-05071-8

Provided by University of Nevada, Las Vegas

Citation: Astronomers Unveil New—and Puzzling—Features of Mysterious Fast Radio Bursts (2022, September 22) Retrieved September 22, 2022, from .html

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