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Astronomers find first evidence of a strange radio bridge connecting two galaxy clusters



For the first time, a colossal magnetic field was observed between two clusters of galaxies. About a billion light-years away, the "bridge" of the radio-emitting plasma spans 10 million light-years, following a thread in the mysterious cosmic web that connects the universe.

The space between galaxy clusters is not completely dark and empty. In between, long strands of diffuse and thin gas and plasma extend; these are called filaments whose entire network forms the cosmic web.

But they are very difficult to study, as weak as they are in a universe where it is only so bright.

Earlier observations with ground-based radio telescopes had & # 39; atria & # 39; of the radio emission, which indicated the presence of a magnetic field in the central area of ​​some clusters ̵

1; some of which contained thousands of galaxies – but no one had ever seen a magnetic field connecting one cluster to another.

The discovery of a magnetic field in the filament between the merging clusters Abell 0399 and Abell 0401 is something out of the ordinary.

"Our group had discovered that both clusters have a radiohalo. More recently, the Planck satellite has shown that the two systems are connected by a thin filament of matter," said astronomer Federica Govoni from the National Institute of Astrophysics in Italy (INAF).

"The presence of this filament has aroused and prompted our curiosity. We want to investigate whether the magnetic field can extend beyond the center of the clusters and penetrate the material filament connecting them."

With the LoFar low-frequency radio telescope consisting of 25,000 antennas At 51 locations, the team sought a home on the thread, noting a "ridge" of low frequency radio radiation that extends between them. Murgia / INAF)

This is a synchrotron radiation produced by electrons that zip at relativistic velocities along the filament. This is only possible if the magnetic field acts as a synchrotron or particle accelerator.

Observe this emission mechanism in individual galaxies and even galaxy clusters, but no radio emission has ever been observed between two of these systems, "said INAF astronomer Matteo Murgia.

But there is a slight hiccup: the Electrons travel far more distances than expected – that is, there must be another element in play, and this element could be the clusters themselves.

Although separated by millions of light-years away, Abell causes 0399 and Abell 0401 is experiencing a major gravitational disturbance in the space around them as they draw inexorably closer to each other.

The team performed computer simulations to see if the dynamics of this fusion affected the acceleration of the electrons, see there, they found an answer. In the simulations, the shock waves generated by the fusion accelerated the high-speed electrons n again, resulting in an emission consistent with the observations of LoFar.

However, this is just one possible mechanism. We will not know for sure until further observations are made.

We also do not know if other filaments also contain magnetic fields, or if it is a property that applies only to Abell 0399 and 0401, or if it is found only in merging galaxies.

We do not know where the pre-existing relativistic electrons came from – their velocity implies an energetic origin that could have ejected them at speed, like supernovae. We also do not know how often these preexisting relativistic electrons occur in the cosmic network.

If their origins are common, such as supernovae, there could be more of them than we ever guessed.

It certainly gives scientists a lot to think about. Not to mention how great it is to see scientists clamoring and paying off.

"With great satisfaction," said Govoni, "the image obtained with the LoFar radio telescope confirmed our intuition and showed what can be defined as a kind of 'aurora' on cosmic scales."

The research was published in Science .


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