⚫ Discovery of a runaway supermassive black hole speeding through space

Astronomers have noticed a long and very unusual luminous trail in their observations. This stretched structure, where stars seem to be born spontaneously, raises a question: what colossal phenomenon could create such a signature in the cosmos?

The answer comes from a recent observation by the James Webb Space Telescope. Astronomers have identified a supermassive black hole, with a mass equivalent to ten million times that of the Sun, moving at a staggering speed of 2.2 million miles per hour (3.5 million km/h). This cosmic monster is apparently fleeing its home galaxy, leaving behind a wake of collapsing matter stretching hundreds of thousands of light-years.


The initial detection was made by the Hubble Space Telescope, which spotted a narrow, unusual trace. To confirm the nature of this object, the team used the advanced capabilities of the JWST. The data revealed a massive displacement of gas at the front of the black hole, forming a shock wave, as well as an elongated tail where matter condenses to give birth to new stars.

Researchers are exploring two possible mechanisms to explain this ejection. When two galaxies collide and merge, their central black holes can interact. If these black holes merge, the emission of gravitational waves can propel the resulting one out of the galaxy (see below). Another possibility involves a three-body interaction between black holes, where one of them is ejected from the system.

This moving black hole could profoundly influence its environment. The shock wave it generates compresses the gas in the regions it passes through, triggering intense star formation (explanation at the end of the article). Although located about 9 billion light-years away in the so-called Cosmic Owl galaxies, its study offers clues about the dynamics of galactic mergers.


The next steps aim to discover other similar examples. With the arrival of new instruments like the Roman Space Telescope, scientists hope to identify these elusive objects more easily. This advance turns a theoretical prediction into observable reality, enriching our understanding of cosmic evolution.

Furthermore, the collected data show that the black hole's speed, deduced from the gas displacement, is sufficient to escape the gravitational pull of its former galaxy.

Gravitational Waves

These ripples in spacetime are predicted by Einstein's theory of general relativity. They occur when massive objects, like black holes or neutron stars, accelerate or collide. Gravitational waves travel at the speed of light, weakly distorting the fabric of space as they pass.

Their direct detection was achieved for the first time in 2015 by the LIGO interferometer. This instrument measures tiny variations in distance caused by the passage of these waves. The captured signals often come from mergers of black holes, releasing enormous energy in the form of gravitational waves.

During galactic mergers, when two supermassive black holes meet, their coalescence emits intense gravitational waves. If this emission is not symmetrical, it can give a recoil kick to the resulting black hole. This "kick" can be strong enough to eject it from its galaxy.

The study of these waves allows testing the fundamental laws of physics under extreme conditions. They also offer a new way to observe the Universe, complementing traditional electromagnetic observations.

Star Formation in Cosmic Wakes

The birth of stars usually occurs within dense clouds of gas and dust in galaxies. Under the effect of gravity, these clouds collapse, forming protostars that eventually ignite through nuclear fusion. This process is often triggered by external disturbances, such as shock waves.

When a massive object, like a runaway black hole, traverses intergalactic space, it creates a bow shock at its front. This wave compresses the surrounding gas, increasing its density and temperature. These conditions favor gravitational collapse, initiating the formation of new stars in the object's wake.

In the case of the observed supermassive black hole, the 200,000 light-year-long tail contains accumulated and shocked gas. This environment becomes an active star-forming site, producing stars with a total mass equivalent to one hundred million times that of the Sun. This phenomenon was previously little known.