Now I report in the newspaper NatureCaltech-led researchers have discovered where FRBs are more likely to occur in the universe: massive star-forming galaxies rather than low-mass galaxies. This discovery has, in turn, led to new ideas about how magnetars themselves form. Specifically, the work suggests that these exotic dead stars, whose magnetic fields are 100 trillion times stronger than Earth’s, often form when two stars merge and later explode in a supernova. Previously, it was unclear whether magnetars formed in this way, from the explosion of two merging stars, or whether they could form when a single star explodes.

“The immense power of magnetars makes them one of the most fascinating and extreme objects in the universe,” says Kritti Sharma, lead author of the new study and a graduate student working with Vikram Ravi, assistant professor of astronomy at Caltech. “Very little is known about the causes of magnetar formation when massive stars die. Our work helps answer this question.”

The project began with a search for FRBs using the Deep Synoptic Array-110 (DSA-110), a Caltech project funded by the National Science Foundation and based at the Owens Valley Radio Observatory near Bishop, California . To date, the sprawling radio array has detected and located 70 FRBs in their specific galaxy of origin (only 23 other FRBs have been located by other telescopes). In the current study, researchers analyzed 30 of these localized FRBs.

“DSA-110 more than doubled the number of FRBs with known host galaxies,” says Ravi. “That’s what we built the network for.”

Although FRBs are known to occur in galaxies that are actively forming stars, the team, to their surprise, found that FRBs tend to occur more often in massive star-forming galaxies than in low-mass star-forming galaxies. This alone was interesting because astronomers previously thought that FRBs occurred in all types of active galaxies.

With this new information, the team began to think about what the results revealed about FRBs. Massive galaxies tend to be rich in metals because the metals in our universe – elements made by stars – take time to accumulate over cosmic history. The fact that FRBs are more common in these metal-rich galaxies implies that the source of FRBs, magnetars, is also more common in these types of galaxies.

Stars rich in metals – which in astronomical terms means elements heavier than hydrogen and helium – tend to grow larger than other stars. “Over time, as galaxies grow, successive generations of stars enrich the galaxies with metals as they evolve and die,” explains Ravi.

Additionally, massive stars that explode as supernovae and can become magnetars are most often found in pairs. In fact, 84% of massive stars are binary. So when a massive star in a binary is bloated due to extra metal content, its excess material is attracted to its partner star, facilitating the ultimate merger of the two stars. These merged stars would have a combined magnetic field greater than that of a single star.

“A star containing more metal swells, causes mass transfer, resulting in a merger, thus forming an even more massive star with a greater total magnetic field than the individual star would have had,” explains Sharma.

In summary, since FRBs are preferentially observed in massive, metal-rich star-forming galaxies, then magnetars (which are thought to trigger FRBs) likely also form in metal-rich environments conducive to star-forming. merger of two stars. The results therefore suggest that the magnetars of the universe come from the remains of stellar mergers.

In the future, the team hopes to track more FRBs and their locations of origin using DSA-110, and eventually DSA-2000, an even larger radio network planned to be built in the desert. Nevada and which will be completed in 2028.

“This result is an important milestone for the entire DSA team. Many of the authors of this paper contributed to the construction of DSA-110,” says Ravi. “And the fact that the DSA-110 is so effective at locating FRBs bodes well for the success of the DSA-2000.”