The universe is riddled with many mysteries for scientists, and one such example is the “Fermi bubbles” that were first discovered in 2010 by the Fermi Gamma-ray Space Telescope.
The symmetrical giant bubbles extend above and below the galactic plane, 25,000 light-years away on each side of the Milky Way’s center, glowing in gamma-ray light – the longer wavelength ranges of energy within the electromagnetic field.
Then, in 2020, the X-ray telescope called eROSITA found another surprise: larger bubbles extending about 50,000 light-years on each side of the galaxy, this time emitting less energetic gamma rays, according to the RT report.
Scientists have since concluded that both groups of bubbles may have been the result of some type of explosion from the galactic center and its supermassive black hole. However, determining the mechanism that produces the gamma rays and X-rays has been a bit trickier.
Now, using simulations, physicist Yutaka Fujita of Tokyo Metropolitan University in Japan has come up with an explanation that can explain the two groups of bubbles, and has shown that the large gamma-ray bubbles around the center of the Milky Way were caused by fast outward winds and the associated “reverse shock”. .
Numerical simulations have succeeded in reproducing the temperature patterns observed with the X-ray telescope, and such outflows have been observed in other galaxies.
This result also indicates that similar winds may have been blowing in our galaxy until very recently. Professor Fujita’s simulation considered that the rapidly flowing wind from the black hole injected the necessary energy into the gas surrounding the center of the galaxy.
And produce “Fermi bubbles”, according to the scientific team, by the fast flowing wind, which blows at a speed of 1000 km per second over 10 million years. These are not winds like those we see on Earth, but streams of highly charged particles traveling at high speeds and spreading through space.
As the wind travels outward and interacts with the surrounding corona gas, charged particles collide with the interstellar medium, which results in a shock wave that bounces back into the bubble (reverse shock).
These reflected shock waves heat the material inside the bubbles, causing them to glow.
The “Fermi bubbles” correspond to the volume inside the front of the reverse shock. Importantly, the simulations also showed that the instantaneous explosion at the center could not reproduce the patterns measured by the telescope, lending weight to a scenario based on the constant winds generated by the central black hole.