The black hole’s slow consumption of the star (artist’s illustration) unleashed a blaze of light that remained bright even five years later. Credit: California Institute of Technology/R. Hurt (AIPAC)
Black holes can get energy boosts by “snacking,” although the dish they choose is somewhat different from ours. The analysis suggests that the brightest burst of light ever detected from a black hole — a fireworks display that at its peak was more than 10 trillion times brighter than the Sun — was sparked when the black hole devoured a star that was at least 30 times more massive than the Sun.
The results were published on November 4 in Nature astronomy1.
When astronomers first laid eyes on the object in 2018, they didn’t realize it was a supernova. After noticing the brightness of the object, the researchers focused on it using the Palomar Observatory Hale 200 inch telescope. But the graph of the light emitted by the object was disappointing. “It didn’t look as interesting as we thought,” says Matthew Graham, an astronomer at the California Institute of Technology in Pasadena and co-author of the paper.
However, in 2023, the team noticed that even after five years, the black hole remained strangely bright. So they took a closer look using the WM Keck Observatory in Hawaii, which revealed that the object was about 3 million kiloparsecs away, or 10 billion light-years. To appear so bright over such a great distance, the light jets must be particularly luminous. Astronomers now say the flare is 30 times brighter than any previously detected optical flare from a black hole.
Trick of light?
The authors investigated several possible causes of the glow. There may have been a supernova near the black hole, or the glow was just a trick of the light, appearing brighter than it actually was due to gravitational effects. But the team found that neither explanation matched the observations well.