Fast radio bursts (FRBs) are among the most energetic events in our universe. These cosmic flashbulbs release more energy in a millisecond than our Sun produces in an entire year. Now, scientists have made a breakthrough discovery about where these mysterious bursts occur: they strongly prefer massive, metal-rich galaxies that are actively forming stars.
“The immense power output of magnetars makes them some of the most fascinating and extreme objects in the universe,” says Kritti Sharma, lead author of the new study published in Nature, in a statement. “Very little is known about what causes the formation of magnetars upon the death of massive stars. Our work helps to answer this question.”
Since their first discovery in 2007, these powerful radio signals have puzzled astronomers. While thousands have been detected, pinpointing their exact locations has proven challenging. That’s where the Deep Synoptic Array-110 (DSA-110), based at the Owens Valley Radio Observatory near Bishop, California, comes in. This impressive radio telescope array has revolutionized FRB research by detecting and precisely locating 70 fast radio bursts to their host galaxies – more than doubling the number of FRBs with known galactic homes.
The research team analyzed 30 of these localized fast radio bursts and made a surprising discovery: these cosmic events aren’t distributed randomly across the universe. Instead, they show a strong preference for occurring in massive galaxies that are actively forming stars. This finding is particularly significant because it challenges previous assumptions that FRBs would occur in all types of star-forming galaxies.
To understand why this matters, we need to look at what makes massive galaxies special. These galactic giants tend to be rich in what astronomers call “metals” – any elements heavier than hydrogen and helium. Think of these metals as the seasoned ingredients in a cosmic cookbook. “Over time, as galaxies grow, successive generations of stars enrich galaxies with metals as they evolve and die,” explains Vikram Ravi, an assistant professor of astronomy at Caltech.
The connection between metal-rich environments and FRBs provides crucial clues about their origins. Scientists believe FRBs are produced by magnetars – highly magnetized neutron stars with magnetic fields 100 trillion times stronger than Earth’s. The new research suggests these exotic dead stars often form through an unexpected process: the merger of two stars that later explode in a supernova.
Here’s where the metal content becomes crucial. Stars rich in metals tend to be larger than their metal-poor counterparts. In fact, 84 percent of massive stars exist in binary systems – pairs of stars orbiting each other. When one star in such a pair becomes enlarged due to its high metal content, its material can be pulled toward its companion star, eventually leading to their merger. As Sharma explains, “A star with more metal content puffs up, drives mass transfer, culminating in a merger, thus forming an even more massive star with a total magnetic field greater than what the individual star would have had.”
This process is similar to how a successful restaurant might emerge from combining two established eateries, pooling their resources and expertise to create something even more impressive. In the cosmic version, the merged stars combine their magnetic fields, potentially creating the conditions necessary for magnetar formation when they eventually explode.
The evidence for this theory comes from studying where FRBs occur. Just as certain neighborhoods might have more successful businesses due to better infrastructure and resources, massive, metal-rich galaxies appear to provide the perfect environment for creating the conditions that lead to fast radio burst production.
Looking ahead, scientists plan to expand their search using both the current DSA-110 array and an even more ambitious project: the DSA-2000, planned for construction in the Nevada desert and scheduled for completion in 2028. “This result is a milestone for the whole DSA team,” says Ravi. “And the fact that the DSA-110 is so good at localizing FRBs bodes well for the success of DSA-2000.”
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