Scientists have long debated the origins of heavy elements like gold and platinum, but identifying their exact sources has been challenging. These elements form through the rapid neutron capture process (r-process), a phenomenon that requires extremely astrophysical conditions.
A new study, using 20-year-old data from NASA and ESA telescopes, reveals a surprising source: giant flares from magnetars, highly magnetized neutron stars. These powerful bursts could account for up to 10% of all elements heavier than iron in our galaxy.
Because magnetars formed early in the universe, this discovery suggests that these energetic flares may have created some of the first gold.
How does magnetar lead to the formation of Gold?
Magnetars occasionally experience starquakes, which crack their neutron star crusts and unleash intense radiation bursts. Some of these quakes trigger giant flares, which are so powerful they can even affect Earth’s atmosphere. So far, scientists have observed three magnetar flares in the Milky Way and Large Magellanic Cloud, and seven more beyond.
First direct distance measurement to magnetar within our Milky Way Galaxy
Researchers, including Patel and his advisor Brian Metzger at Columbia University, suggest that these flares could play a role in forming heavy elements. In these extreme conditions, neutrons rapidly fuse with lighter atomic nuclei, creating heavier elements.
On the periodic table, protons determine an element’s identity, while neutrons add mass. When an atom gains an extra neutron, it can become unstable and undergo nuclear decay, converting the neutron into a proton and shifting its identity. For example, gold could absorb a neutron and then transform into mercury.
In the extreme environment of a disrupted neutron star, where neutron density is incredibly high, atoms can rapidly absorb multiple neutrons, undergoing several decay processes until they form heavier elements like uranium.
Astronomers confirmed in 2017 that neutron star mergers can create gold, platinum, and other heavy elements, based on observations from NASA telescopes, LIGO, and multiple ground-based observatories. However, these mergers occur too late in cosmic history to explain the earliest heavy elements.
Recent studies by Jakub Cehula (Charles University), Todd Thompson (Ohio State University), and Brian Metzger (Columbia University) suggest that magnetar flares—violent bursts from highly magnetized neutron stars—could be an earlier source of heavy elements. These flares heat and eject neutron-rich crustal material, potentially seeding the early universe with gold and other elements.
Initially, Metzger and colleagues predicted that magnetar flare-created elements would be visible in both visible and ultraviolet light. However, Burns (Louisiana) proposed checking for a gamma-ray signal, leading researchers to confirm such a signature, offering further evidence that magnetar flares might play a role in element formation.
The best look ever at a giant flare
“At some point, we said, ‘OK, we should ask the observers if they had seen any,’” Metzger said.
Burns revisited gamma-ray data from the December 2004 magnetar flare and found a small signal in observations from ESA’s INTEGRAL mission, a now-retired spacecraft with NASA contributions. While scientists had previously noted the signal, its significance was unclear at the time.
When Burns shared his findings with Metzger and Patel, they realized the 2004 gamma-ray signal matched their predicted model for how heavy elements form and spread during a magnetar giant flare. Metzger recalled thinking Burns was joking because the data aligned so precisely with their theoretical predictions.
Patel was so excited, “I wasn’t thinking about anything else for the next week or two. It was the only thing on my mind,” he said.
Researchers supported their conclusion using data from two NASA heliophysics missions: the retired RHESSI (Reuven Ramaty High Energy Solar Spectroscopic Imager) and the ongoing NASA Wind satellite, which had also observed the magnetar giant flare. Other collaborators on the new study included Jared Goldberg at the Flatiron Institute.
Journal Reference:
- Anirudh Patel, Brian D. Metzger, Jakub Cehula, Eric Burns, Jared A. Goldberg, and Todd A. Thompson. Direct Evidence for r-process Nucleosynthesis in Delayed MeV Emission from the SGR 1806–20 Magnetar Giant Flare. The Astrophysical Journal Letters. DOI: 10.3847/2041-8213/adc9b0
