The universe has always been filled with mysteries, one of which is the origin of elements heavier than iron, such as gold. Since the universe’s inception, only hydrogen, helium, and trace amounts of lithium were present. As time progressed, stars began to forge heavier elements like iron, but the creation and dissemination of elements heavier than iron have puzzled astrophysicists for decades. This enigma has persisted in understanding the complex matter’s birth in the universe.
Astrophysicists have been on a quest to uncover the origins of these heavier elements. Anirudh Patel, a doctoral student at Columbia University in New York, is among those leading the charge. "It’s a fundamental question regarding the universe’s complex matter origin," Patel notes. His research, in collaboration with other scientists, has uncovered new insights using 20-year-old data from NASA and the European Space Agency’s (ESA) telescopes. This study, recently published in The Astrophysical Journal Letters, highlights a surprising source for these elements: flares from magnetars, which are highly magnetized neutron stars.
The research suggests that these magnetar giant flares may contribute up to 10% of the galaxy’s total abundance of elements heavier than iron. This revelation implies that magnetars, which have existed since the early universe, could have been responsible for the formation of the first gold.
Eric Burns, a co-author of the study and an astrophysicist at Louisiana State University, emphasizes the significance of this discovery. "We’re addressing one of the century’s questions and solving a mystery using archival data that was nearly forgotten," Burns explains.
Neutron stars are the remnants of stars that have undergone a colossal explosion, leaving behind dense cores. These stars are so dense that a teaspoon of their material would weigh as much as a billion tons here on Earth. Magnetars, a type of neutron star, possess extraordinarily powerful magnetic fields. Occasionally, these magnetars experience "starquakes," akin to earthquakes, which cause their crusts to fracture. These events can lead to the release of intense bursts of high-energy radiation known as magnetar giant flares. Such flares are rare, with only a few detected in our galaxy and nearby galaxies.
Patel, along with his advisor Brian Metzger, a professor at Columbia University and senior research scientist at the Flatiron Institute, have been exploring how radiation from these giant flares could facilitate the formation of heavy elements. The process involves a rapid neutron capture, where lighter atomic nuclei are transformed into heavier ones. This process is fundamental to understanding how elements are formed at a nuclear level.
In the unique setting of a disrupted neutron star, the density of neutrons is incredibly high. Atoms can capture numerous neutrons, leading to multiple decay processes and the creation of much heavier elements, such as uranium.
The 2017 observation of two neutron stars colliding was a groundbreaking event for astronomers. This collision, observed using NASA telescopes and the Laser Interferometer Gravitational-Wave Observatory (LIGO), along with numerous other telescopes, confirmed that such events could produce heavy elements like gold and platinum. However, these mergers occur too late in the universe’s timeline to explain the earliest presence of gold and other heavy elements. Recent research by co-authors of the new study, including Jakub Cehula from Charles University in Prague and Todd Thompson from The Ohio State University, suggests that magnetar flares, which can eject neutron star crustal material at high velocities, could be a potential source for these elements.
Initially, Metzger and his team anticipated that the production and dispersal of heavy elements at a magnetar would be visible in ultraviolet and visible light. However, Burns proposed the possibility of a detectable gamma-ray signal. After examining gamma-ray data from the last observed giant flare in December 2004, they discovered a smaller signal, which had been previously noted but not understood. This signal matched the predicted signature of heavy element creation and distribution during a magnetar giant flare.
The team validated their findings using data from two NASA heliophysics missions: the retired RHESSI (Reuven Ramaty High Energy Solar Spectroscopic Imager) and the ongoing NASA’s Wind satellite. These missions also observed the magnetar giant flare, further reinforcing the study’s conclusions. Other collaborators, such as Jared Goldberg from the Flatiron Institute, contributed to this groundbreaking research.
Looking to the future, NASA’s upcoming COSI (Compton Spectrometer and Imager) mission is poised to build on these results. Scheduled for launch in 2027, COSI is a wide-field gamma-ray telescope designed to study energetic cosmic phenomena, including magnetar giant flares. It will have the capability to identify individual elements created in these events, offering a significant advancement in our understanding of element origins. COSI is one of many telescopes that collaborate to observe transient changes across the universe.
Researchers are also delving into other archival data, hoping to uncover more secrets hidden in observations of other magnetar giant flares. Patel reflects on the broader implications of this research, marveling at how materials in everyday items like phones and laptops may have been forged in these extreme cosmic explosions over the course of our galaxy’s history.
For more information about magnetars and their role in the universe, you can explore NASA’s dedicated page on this topic at NASA Magnetars.
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