Space mystery ‘Fermi bubble’ may have originated from a black hole jet 6 million years ago

According tomedia reports, the center of the Milky Way is like a “jigsaw puzzle” of interconnected, invisible structures. Only at radio wavelengths can we see the surge of energy, the hourglass-shaped X-ray structure, and the mysterious structure that rises above everything, the Fermi Bubble. A new study suggests that the double-conical X-ray outflow of feroa bubbles and the center of the Milky Way may be essentially the same phenomenon.

Space mystery 'Fermi bubble' may have originated from a black hole jet 6 million years ago

The huge Fermi bubbles can only be seen in the gamma-ray band.

Ten years ago, the Fermi Gamma-ray Space Telescope discovered a symmetrical bubble-like structure at the center of the Milky Way, known as the Fermi bubble, whose origins have been a puzzle for scientists. Fermi bubbles are two giant spheroidal structures of gas, dust and cosmic rays that are like a pair of giant moth wings at the center of the Milky Way, separating the sides of the supermassive black hole at the center of the Milky Way. The distance between the ends of the Fermi bubble is about 50,000 light-years (half the diameter of the Milky Way), but can only be seen in the high-energy gamma-ray band.

Where do they come from? No one knows the exact answer. However, a study published May 14 in the Astrophysical Journal suggests that these bubbles, along with mysterious X-rays and radio structures that surround the center of the Milky Way, are linked to a series of black hole activity that began about 6 million years ago.

Space mystery 'Fermi bubble' may have originated from a black hole jet 6 million years ago  

The image shows where the Fermi bubble (red) overlaps the hourglass X-ray structure (black) at the center of the Milky Way. The edges of the two structures appear to fit perfectly, according to a new study.

Researchers at the Shanghai Observatory in China have shown through several computer simulations that fermi bubbles and nearby X-ray structures may have been formed by huge shock waves from the black hole at the center of the Milky Way, also known as the Constellation of Man A or Sgr A. The shock waves may begin when a black hole suddenly releases two huge ionized streams of material that fly at near-speed of light in the opposite direction away from the center of the Milky Way. Astronomers have previously observed such jets erupting in galaxies with large black holes, but they are not sure why.

If the jets were wide enough and strong enough, they could produce two shock waves that would penetrate the hot gas on both sides of the milky center, the researchers wrote. Where the shock compresses and heats the gas, an hourglass-like X-ray structure is formed, and the edges of the shock wave extend thousands of light-years in both directions, forming fermi bubbles. The whole process could last about a million years, the team wrote.

“When the jet stream hits the surrounding halo gas, it produces a positive shock wave,” the researchers wrote in the paper. After 5 million years, the bubbles swell to their current size. “In this new model, the supermassive black hole, The Mare a. Samaritan, atotalised about 100 times the solar mass in the Fermi bubble, releasing the equivalent of the total energy released by 20,000 supernova eruptions.

The researchers say the forward-wave hypothesis explains several features of the center of the Milky Way, including the extremely high temperature of the Fermi bubbles and the perfect coincident of the bottom edge of the bubbles with the X-ray structure. They also point out that if there had been another similar but low-intensity shock event in the years after the event, it could explain the smaller, bubble-like radio structure recently observed at the center of the Milky Way. In other words, the three giant, invisible pieces of “jigsaw puzzle” at the center of the Milky Way may be more closely related than scientists thought.