Astronomers have detected radio emissions from a bridge linking two galaxy clusters in slow, inevitable collision about a billion light-years away from Earth.
It's the first time this phenomenon has ever been observed, and scientists are hoping it can reveal new insights about the universe on a larger scale.
The Universe's Invisible Web
The universe is impossibly vast, but it doesn't just consist of empty space with clusters consisting of hundreds or even thousands of galaxies scattered throughout the cosmos.
These galaxy clusters are connected by long strands of plasma that could extend for many millions of light-years. These galactic bridges are known as filaments with dust, gas, and even electrons traveling along them at incredibly rapid speeds.
A network of these threads is strung across the universe, like a massive invisible web in the sky.
Finding A Magnetic Field Within The Filaments
Now, in a new study published in the journal Science, researchers reveal evidence of a magnetic field existing along a filament. It stretches 10 million light-years between the pair of galaxy clusters Abell 0399 and Abell 0401.
"Radio emission connecting clusters has never been observed before," study author Federica Govoni of Italy's National Institute for Astrophysics told National Geographic.
While astronomers are capable of observing galaxy clusters due to the abundance of hot gas, dark matter, and stars within them, it's extremely difficult to see anything between these clusters. Since there's hardly anything in this space, very few techniques work in seeing anything from Earth.
Regardless of the odds of seeing anything, Govoni and her team took a look at the space between Abell 0399 and Abell 0401 using Europe's array of radio telescopes known as the Low-Frequency Array.
Their efforts paid off immensely. With LOFAR, they were able to see a ridge of tell-tale radio emissions linking the two galaxy clusters together. These so-called synchrotron emissions are produced by electrons spiraling around magnetic fields at near light-speed.
The team also successfully estimated the strength of the magnetic field, which is only about 1 million times weaker than the Earth's magnetic field.
A Mystery Left To Solve
The discovery of a magnetic field within a filament has left scientists wondering exactly how synchrotron emissions are produced at such a vast space.
Particles are not known to travel long distances and often break down just a fraction of the filament's entire stretch. Even if particles approach the speed of light, the expanse between two galaxy clusters is simply too great a distance for an electron to remain in acceleration — supposedly.
After simulations, the team found that it's possible for a magnetic field to create shockwaves that are strong enough to keep re-accelerating the electrons and maintain their trajectory from one end of the filament to the other.
Of course, this is only one potential explanation for the newly detected radio emissions. There's much more to learn, and scientists will be diving into the data to uncover more knowledge about the universe's mysterious structure.
"This opens a whole new set of doors to begin exploring things like the particle distribution in the filaments, the magnetic field strength — and potentially its origin — as well as acceleration or reaccelerating processes at work within the filaments," astronomer Tracy Clarke of the U.S. Naval Research Laboratory said in National Geographic.
