Fluctuations in the light emitted by the brightest galaxies in the universe could reveal a secret at their heart, astronomers say.

According to a new analysis of a type of galaxy known as a blazar, the best explanation for the unusual changes in their glow is a pair of supermassive black holes trapped in a decaying orbit.

Led by astronomer Silke Pritzen of the Max Planck Institute for Radio Astronomy in Germany, an international team studied 12 massive galaxies and found that the explanation for circular black holes can be applied to all of them.

This could be evidence of how supermassive black holes with masses millions to billions of times the mass of the Sun grow to such massive sizes. A large number of supermassive black hole binaries point to giant mergers throughout the history of the universe.

“We provide evidence and discuss the possibility that it is in fact an advancing motion of the jet’s source, either due to a supermassive black hole binary at the foot of the jet or – more likely – due to an accretion disc twisting around a single black hole,” Britzen says. “This is what is responsible for the observed asymmetry.” “.

The brightest known objects in the universe are quasars — galaxies with a supermassive black hole at their center, which is actively gobbling up material from a massive, hot disk swirling around it like water in a drain.

A blazar is a type of quasar that is oriented in a certain way. As matter orbits the black hole, some of it is diverted and accelerated along magnetic field lines beyond the event horizon to the poles, where it is launched into space as jets of plasma approaching the speed of light. In bright galaxies, one of these jets is directed directly at us.

But there’s something strange about the light emanating from brightness: it varies in intensity. This has previously been interpreted as random, or stochastic, perhaps the result of blobs of material being injected into the jets, causing what appears to be a glow.

A few years ago, Britzen and her colleagues showed that the anisotropy of blazar OJ 287 was the result of a jet. This means that the flow source oscillates like a rotating top, causing the jet itself to bend and oscillate as well. We also know that OJ 287 hosts two supermassive black holes; The initiative is related to their orbit.

OJ 287 is a bit of an extreme case; Its volatility is very clear. But using the same framework on 11 other flares with less pronounced fluctuations, as well as OJ 287, the researchers found that precession plays an important role in their fluctuations.

Other processes, such as blobs and shocks, may also be present, but the fundamental precession should not be ignored in explaining why the jets appear the way they do, the researchers say.

“The physics of accretion discs and jets is rather complex, but their large kinematics can be compared to simple gyroscopes,” explains astrophysicist Michal Zajacek of Masaryk University in the Czech Republic.

“If you exert an external torque on an accretion disk, for example by an orbiting secondary black hole, it will move and rotate, and with it the jet as well, similar to the Earth’s rotation axis being affected by the Moon and the Sun.”

We currently lack the tools to observe the disk structure that would reveal these binary black holes, but ongoing monitoring of the precession, as well as long-term monitoring of other crystals, could continue to provide information about their presence.

“Jet motion appears to provide the best signature for these objects, the existence of which is predicted not only by the black hole/AGN community, but also by the gravitational wave/pulsar community which recently published evidence of the existence of a cosmic gravitational background due to emitted gravitational waves,” Britzen says. From the merger of massive black holes throughout cosmic history.”

The research was published in Astrophysical Journal.