When you peer into the heart of a galaxy long enough to spot the black hole lurking there, that might not be all you might catch. When a major collaboration pointed telescopes around the world into the heart of the M87 galaxy in 2018 in a successful attempt to capture details of the supermassive black hole, they also managed to observe some of the crazy antics a black hole performs.

Astronomers have now discovered that one of these ramblings is a giant belch, a burst of gamma radiation from one of the powerful plasma jets emitted from the black hole’s poles as it feeds.

“We were lucky to detect a gamma-ray burst from M87 during the Event Horizon Telescope’s multiwavelength campaign,” says astrophysicist Giacomo Principe of the University of Trieste in Italy. “This is the first gamma-ray burst observed from this source in decades, allowing us to precisely constrain the size of the region responsible for the observed gamma-ray emission.”

Located 55 million light-years from the Milky Way, M87 was chosen for the first human image of the shadow of a supermassive black hole because its central black hole is actively pulling material from the massive cloud of material around it.

Frictional and gravitational forces acting on the cloud of material heat it and cause it to glow. This is the source of the dotted light you see in the M87* image. But a feeding supermassive black hole often exhibits another phenomenon: astrophysical jets.

Scientists believe these are caused by the interaction between the material and the black hole’s external magnetic field. As material falls from the inner edge of the disk of gas and dust orbiting the black hole, some of it is deflected along magnetic field lines beyond the event horizon, like water around a drain. It is thrown into space at tremendous speed, accelerating towards the poles and approaching the speed of light in vacuum.

These are astrophysical jets, and M87 is a highlight. Observations of black holes in the galaxy have helped scientists better understand this process, thanks to the most detailed observations of the region from which the jets are ejected. Jets from a supermassive black hole flowing from a galaxy into intergalactic space can interact with the objects they collide with, creating some pretty wild turbulence.

Gamma-ray bursts sometimes observed from these jets are thought to be the result of clumps of material entering the jet being accelerated to extremely high energies, resulting in high-energy gamma-ray bursts.

As you can imagine, this makes them a bit unpredictable. You cannot plan observations; You just have to hope you’re looking in the right place at the right time. The flare captured by the Event Horizon telescope was incredible. It took three days; This corresponds to a radiation field of less than 170 AU – approximately 170 times the distance between the Earth and the Sun.

“The rapid variability of gamma rays indicates that the flare region is extremely small, only ten times the size of the central black hole,” explains astrophysicist Daniel Mazin from the University of Tokyo.

“Interestingly, the sharp variability observed in gamma rays was not detected at other wavelengths, indicating that the flare region has a complex structure and exhibits different properties depending on wavelength.”

Interestingly, the asymmetry of the halo around the black hole changed depending on the brightness. Asymmetry manifests itself as brighter and dimmer areas of the ring; When the flare was observed, these points of relative brightness and dimness moved, suggesting a relationship between the ring and the flare.

The nature of the relationship currently remains a mystery; Researchers have not been able to pinpoint the source of the gamma radiation or what causes it. But the observations give us new information that can help constrain future research efforts.

“How and where particles are accelerated in supermassive black hole jets is a long-standing mystery,” says theoretical astrophysicist Sera Markoff of the University of Amsterdam. “For the first time, we can combine direct imaging of regions near the event horizon during gamma-ray bursts from particle acceleration events and test theories about the origin of the bursts.” The study was published on: Astronomy and Astrophysics.