Perhaps scientists have solved a great mystery

The Universe is still the source of great mysteries, and scientists continue to study in an effort to expand our knowledge of what goes on in deep space. Thanks to the efforts of a Japanese physicist, perhaps today we have dissolved the doubts about the origin of Fermi bubblestwo gigantic accumulations of gas deposited on the sides of the Milky Way, from which powerful gamma rays are emitted.

What are Fermi bubbles?

In 2008, the Fermi Gamma-Ray Space Telescope it was launched into orbit by NASA with the aim of studying the electromagnetic radiation emitted by celestial bodies. Just a couple of years later, this powerful instrument allowed us to discover the existence of two giant spots placed symmetrically on the sides of the Milky Way, and more precisely below and above the galactic plane. Both extend about 25,000 light-years from the center of the galaxy and produce gamma rays – which is why, while invisible to the naked eye, they appeared in all their magnificence at the NASA telescope.

These two structures, filled with very hot gas, have been called Fermi bubbles. Scientists have always considered their origin a real mystery and, to complicate matters, another peculiar discovery took place in 2020. The X-ray telescope called eROSITA has spotted two more bigger bubbles (extend 45,000 light-years from the center of the galaxy) which emit radiation of less power. Scientists began to speculate that both sets of bubbles were the result of an explosion from the galactic center or from the supermassive black hole inside. But how do these bubbles produce gamma rays and X-rays?

The theory that explains the origin of Fermi bubbles

A Japanese physicist may have finally found the explanation for this mystery. The Professor Yutaka Fujita, of Tokyo Metropolitan University, has identified something that both sets of bubbles have in common and that could answer many questions about their origin. At the center of the Milky Way is a supermassive black hole called Sagittarius A*: although today it is in a state of quiescence, in the past it was protagonist of a fervent activity – of which we can find several testimonies in the space closest to our galaxy.

The Fermi bubbles would be just a proof of the effects that a black hole could have in the Universe. These gamma and X-ray producing spots may have arisen from very fast winds coming out of the galaxy, which hit the gas that fills interstellar space generating a shock wave that reverberates through the energetic glow that we can still admire today. The most plausible scenario, according to Fujita, would be that of the wind coming from the black hole that it blows at about 1,000 km/swhich would have propagated for a good 10 million years, dying out only recently.

To arrive at these results, the Japanese physicist made use of the data extrapolated from X-ray satellite Suzaku, then performing numerous numerical simulations to reproduce Fermi bubbles based on the activities of black holes. Professor Fujita’s conclusions were recently published in Monthly Notices of the Royal Astronomical Societyand they could finally give a satisfactory explanation to what it was one of the most curious mysteries concerning our Milky Way.