Fast radio bursts are more mysterious than we thought •

Fast radio bursts (FRBs) are intense pulses of radio wave energy that typically last only a millisecond and come from somewhere deep in the universe. Astrophysicists detect these signals mostly from far away galaxies, but they have not yet understood the origin of pulses. The eruptions are very intense at their source, releasing as much energy in a fraction of a second as the Sun does in an entire day. However, by the time they reach land, they are very weak and difficult to detect.

A new study published in the journal temper nature It was co-authored with 74 co-authors from 30 different institutions and has now provided details of the largest sample of FRB data obtained from a single source. Unfortunately, rather than furthering our understanding of this remarkable phenomenon, the observations have simply deepened its mystery.

Observations of the cosmic fast radio burst were made in late spring 2021 with the Five Hundred-meter Aperture Spherical Radio Telescope (FAST) in China. The team, led by Heng Shuo, Qijia Li and Subo Dong of Peking University, and Weiwei Zhou of the National Astronomical Observatories of China, along with an astrophysicist Bing Chang From University of Nevada, Las Vegas, 1863 radio bursts were detected in 82 hours over 54 days from an active source called FRB 20201124A. “This is the largest sample of FRB data with polarization information from a single source,” Lee told me.

Some observations of FRBs from within our galaxy suggest that they originated from magnetars, which are dense, city-sized neutron stars with incredibly strong magnetic fields and the ability to release massive amounts of energy. For example, in April 2020 astronomers discovered a FRB coming from Inside our Milky Way And fixed its location on a known magnetic star, SGR 1935 + 2154. However, the exact origin and cause of FRBs from other distant galaxies remains undetermined, with many people suggesting the rapid rotation neutron stars, Black holes or even extraterrestrial intelligence.

The latest observations leave scientists more in the dark than they were before, wondering what they think they know about FRBs. “These observations brought us back to the drawing board,” said Zhang, who is also the founding director of UNLV’s Nevada Center for Astrophysics. “FRBs are clearly more enigmatic than we imagined. More multi-wavelength observational campaigns are needed to further reveal the nature of these organisms.”

What makes the recent observations surprising to scientists are the irregular and short variations of the so-called “Faraday spin scale,” a measure of magnetic field strength and particle density in the vicinity of a fast radio burst source. These measurements varied increasing and decreasing during the first 36 days of observation, then abruptly stopped varying and became constant for the remaining 18 days before the source became silent.

“I’m like shooting a movie about the surroundings of an FRB source, and our film revealed a complex, dynamically evolving magneto-environment that had never been imagined before,” Zhang said. “Such an environment is not directly predictable for an isolated magnetar. There may be something else near the FRB engine, possibly a binary companion,” Chang postulated.

To observe the galaxy that hosted the source of the FRBs in the current study, the team also used the 10-meter Keck telescopes located on Mauna Kea in Hawaii. Zhang says he believes young magnetars live in the active star-forming regions of a star-forming host galaxy. But when the researchers investigated the host galaxy’s optical image for current FRB signals, they showed, unexpectedly, that the host galaxy is a mineral-rich spiral galaxy that, like our Milky Way, has no significant region with star formation. Activity.

“This location is inconsistent with a young centromagnetic drive formed during an intense explosion, such as a long gamma-ray burst or ultra-bright supernova, which are widely expected predecessors to energetic FRBs,” Dong said.

Therefore, for the time being at least, FRBs remain mysterious signals of some process taking place in distant galaxies, and their cause or source remains mysterious and perplexing.

by Alison BosmanAnd the crew clerk