The metals, which in astronomy include any element heavier than hydrogen or helium, were detected as heat signatures from specific gas clouds billowing near the black hole. Researchers from McGill University and other institutions analysed the JWST data and found that the gas has a similar composition to several nearby stars, suggesting both originated from the same supernova explosions.
“We know there’s a black hole at the centre of our galaxy pulling material into itself, but we see that it’s eating a lot less material than other supermassive black holes, and more slowly,” said Nicole Ford, first author of the new paper and a doctoral student in astrophysics at McGill. “Part of understanding why this is happening means looking at the properties of the materials available for it to consume, including gas, dust and the stars orbiting around it.”
The study builds on work published in The Astrophysical Journal in May, which showed that gas emissions near the black hole have been influenced by conditions in the local clouds. That earlier work also indicated that the gas alone cannot serve as a reliable proxy for how often the black hole has been active, complicating efforts to reconstruct its past.
JWST orbits at a point about 1.5 million kilometres from Earth, opposite the sun. The telescope’s ability to identify the heat signatures of gas clouds allowed the team to measure their metal content directly.
McGill researchers said the findings could advance understanding of how metals are distributed around supermassive black holes in more distant galaxies, as well as the processes that supplied Earth with many of its heavy elements. The presence of metals, they noted, influences how quickly gases cool, which in turn affects how readily the gas can be drawn into a black hole.