Fast radio bursts (FRBs) are millisecond-long events detected from beyond the Milky Way. The radiative properties of FRBs favor magnetars as their source, as evidenced by FRB-like outbursts from the Milky Way's magnetars and the star-forming nature of FRB host galaxies. However, the process that generates the FRB source remains unknown. FRBs are more likely to occur in massive star-forming galaxies, according to a new study. The study also suggests that magnetars, whose magnetic fields are 100 trillion times stronger than Earth's, are often formed when two stars merge and later explode in a supernova.
This photo montage shows the Deep Synoptic Array-110 antenna used to locate and determine the location of Fast Radio Bursts (FRBs). Above the antenna are several images of the FRB's host galaxy appearing in the sky. These galaxies are very large and challenging models to describe FRB sources. Image credit: Annie Mejia/California Institute of Technology.
“Magnetars' immense power output makes them one of the most fascinating and extreme objects in the universe,” said lead author Kriti Sharma, a graduate student at Caltech.
“Little is known about what causes magnetars to form during the extinction of massive stars. Our work helps answer this question.”
To search for FRBs, Sharma and his colleagues used Deep Synoptic Array-110 (DSA-110) at the Owens Valley Radio Astronomical Observatory near Bishop, California.
To date, this sprawling radio array has detected 70 FRBs and located their specific source galaxies (only 23 other FRBs have been located by other telescopes). is).
In the current study, the researchers analyzed 30 of these local FRBs.
“DSA-110 more than doubles the number of FRBs containing known host galaxies, which is what we built the array for,” said Dr. Vikram Ravi of the California Institute of Technology.
FRBs are known to occur in galaxies that are actively forming stars, but the authors were surprised to find that FRBs are more frequent in massive star-forming galaxies than in low-mass star-forming galaxies. I've found that this tends to happen.
This alone was interesting because astronomers had previously thought that all types of active galaxies generate FRBs.
Armed with this new information, they began pondering what the results revealed about the Fed.
Metals in our universe (elements manufactured by stars) take time to accumulate over the course of the universe's history, so large galaxies tend to be rich in metals.
The fact that FRBs are more common in these metal-rich galaxies means that the magnetars from which they originate are also more common in these types of galaxies.
Stars rich in metals (astronomical terminology for elements heavier than hydrogen or helium) tend to be larger than other stars.
“Over time, as the galaxy grows, successive generations of stars evolve and die, enriching the galaxy with metals,” Dr. Ravi said.
Additionally, massive stars that can go supernova and become magnetars are more commonly found in pairs.
In fact, 84% of massive stars are binaries. So when one massive star in a binary swells with extra metal content, that extra material is pulled into its partner, which facilitates the eventual merger of the two stars.
These merging stars will have a combined magnetic field that is larger than the magnetic field of a single star.
“Stars with more metallic content swell, promoting mass transfer and eventually reaching mergers, resulting in even more massive stars with a total magnetic field greater than what any individual star would have.” is formed,” Sharma said.
In summary, since FRBs are preferentially observed in massive, metal-rich star-forming galaxies, magnetars (which are thought to cause FRBs) are also probably located in metal-rich environments that promote the merger of two stars. It is thought that it is formed by.
Therefore, this result suggests that magnetars in the universe originate from the remains of stellar mergers.
In the future, the team plans to use the DSA-110 and eventually the DSA-2000, an even larger wireless array to be built in the Nevada desert and expected to be completed in 2028, to connect more FRBs and their We would like to track the location of the occurrence.
“This result is a milestone for the entire DSA team. Many of the authors of this paper helped build DSA-110,” said Dr. Ravi.
“And the fact that DSA-110 is so good at localizing FRBs bodes well for the success of DSA-2000.”
of findings Published in today's magazine nature.
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K. Sharma others. 2024. Preferential occurrence of fast radio bursts in massive star-forming galaxies. nature 635, 61-66; doi: 10.1038/s41586-024-08074-9
Source: www.sci.news
