Galaxy cluster emitting X-rays might be a giant particle accelerator

Paris, Jan 25: European Space Agency’s orbiting gamma-ray observatory, Integral, has made the first unmistakable discovery of highly energetic X-rays coming from a galaxy cluster, which seems like a giant particle accelerator.

According to ESA, the X-rays are originating from the Ophiuchus galaxy cluster.

Because, the X-rays detected are too energetic to originate from inactive hot gas inside the galaxy cluster, scientists suggest that giant shockwaves must be rippling through the gas.

This has turned the galaxy cluster into a giant particle accelerator.

Four years ago, data from the Italian/ Dutch BeppoSAX satellite showed a possible extra component of high-energy X-rays, but in a different cluster, the Coma cluster.

"Two groups analysed the data. One group saw the component but the other did not," said Dominique Eckert, Integral Science Data Centre (ISDC), University of Geneva, Switzerland.

This prompted Eckert and colleagues from ISDC to launch an investigation into the mystery.

These scientists then turned to Integral’s five-year, all-sky survey, and found that ESA's orbiting gamma-ray observatory did show an unambiguous detection of highly energetic X-rays, coming from the Ophiuchus cluster of galaxies.

These X-rays can be produced in two ways, both of which involve high-energy electrons.

The first option is that the electrons are caught in the magnetic field threading through the cluster. In this case, the electrons will spiral around the magnetic field lines, releasing synchrotron radiation in the form of X-rays.

The electrons will be extremely energetic, carrying over 100 000 times the energy of the electrons in the alternative scenario, which is that the electrons are perhaps colliding with microwaves left over from the origin of the Universe and now bathe all of space.

In such collisions, the electrons lose some energy, emitted as X-rays.

Either way, the electrons themselves are most likely to be accelerated to high energies by shockwaves travelling through the cluster gas. The shockwaves are set up when two clusters collide and merge.

Determining which of these scenarios is correct is the next job for the team. They plan to use radio telescopes to measure the magnetic field of the galaxy cluster.

Though the research might enable scientists to properly understand the history of the cluster, one thing is already certain; nature has transformed the galaxy cluster into a powerful particle accelerator. (ANI)