Gargantuan Gamma-Ray Flare Seen Spewing From Supermassive Black Hole

A group of researchers recently saw a flash of gamma-rays from a distant supermassive black hole that was tens of millions of times larger than the black hole’s event horizon—the region beyond which not even light can escape it.

The gamma-ray flare emitted photons billions of times more energetic than visible light, making it the most intense flare observed in over a decade. It lasted about three days and, based on the team’s analysis, was emitted from a region less than three light-days across, or just under 15 billion miles (24 billion kilometers). The research—published today in Astronomy & Astrophysics—describes the extreme environment surrounding the M87 black hole (which is conveniently and confusingly also called M87).

Over 300 scientists co-authored the paper, which explores the physics of the black hole. This cosmic phenomenon pulls matter toward its maw and energizes surrounding particles, launching them into massive jets of material. These jets smash into objects in the surrounding cosmic environment and can be gigantic; a pair of jets described in September are 140 times longer the Milky Way galaxy is wide.

A light curve of the gamma-ray flare (bluish, at bottom), and other simulated images of the M87 jet. Graphic: EHT Collaboration, Fermi-LAT Collaboration, H.E.S.S. Collaboration, MAGIC Collaboration, VERITAS Collaboration, EAVN Collaboration

“We still don’t fully understand how particles are accelerated near the black hole or within the jet,” said Weidong Jin, a researcher at UCLA and corresponding author of the paper, in a university release. “These particles are so energetic, they’re traveling near the speed of light, and we want to understand where and how they gain such energy. Our study presents the most comprehensive spectral data ever collected for this galaxy, along with modeling to shed light on these processes.”

The team found a variation between the event horizon’s position and angle and the position of the black hole’s jet, indicating that the interactions between particles and the event horizon influences the jet’s position.

“These efforts promise to shed light on the disk-jet connection and uncover the origins and mechanisms behind the gamma-ray photon emission,” said Giacomo Principe, a researcher at the University of Trieste and co-author of the paper, in a Center for Astrophysics | Harvard & Smithsonian release.

Only two black holes have been directly imaged so far. Since light cannot escape their event horizons, when we say “directly imaged,” we mean the black hole’s shadow has been directly imaged at the center of the energetic, light-emitting accretion disk. The supermassive black hole at the center of galaxy M87 was dramatically revealed in 2019, the first to be imaged by humankind.

Follow-up observations indicated that the black hole is wobbling, and has a fluffier ring than previously thought. The Event Horizon Telescope collaboration took the image of M87, and followed up on it with an image of Sagittarius A*, the black hole at the center of our galaxy, in 2022.

“Observations—both recent ones with a more sensitive EHT array and those planned for the coming years—will provide invaluable insights and an extraordinary opportunity to study the physics surrounding M87’s supermassive black hole,” Principe added.

As imaging techniques improve, as well as the models astrophysicists use to understand these distant and extreme environments, we will get a better look at some of the structures shaping our universe. Keying into these details of the universe could in turn yield new discoveries about the bounds of classical physics as we know them.