Giant "bubbles" spotted around the black hole of the Milky Way

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In his first major achievement, just over a year after its inauguration, a super sensitive South African telescope he discovered two gigantic "radio bubbles" above and below the central region of the Milky Way. The characteristics extend over a total of 430 parsecs (1,400 light years), about 5% of the distance between the solar system and the center of the galaxy.

Bubbles are gas structures that can be observed because the electrons that move inside them produce radio waves while they are accelerated by magnetic fields. This activity suggests that the bubbles are the remains of a hot gas energy eruption several million years ago, say the authors of a document describing the features, published in Nature September 11th.

One possible explanation is that the super massive black hole in the center of the Galaxy has undergone a period of intense devouring the matter that created the explosion, the researchers say. Another could be a "starburst" event: the almost simultaneous formation and the subsequent burning death of about 100 big stars. The shock waves of their explosions could have combined to make a hole in the dense interstellar matter of the central region of the Galaxy.

Oliver Pfuhl, an astronomer at the Southern European Observatory in Garching, Germany, states that it is the activity of starburst and that of the black hole that may have been at stake, even strengthening each other. And the researchers know of a starburst that took place in the region about 7 million years ago. "It is interesting to relate the radio bubble with this star formation event," he says.

Researchers who worked with the MeerKAT radio telescope in South Africa, a precursor of what will be the largest radio telescope in the world, the Square Kilometer Array (SKA), discovered the bubbles when they created a image of the galactic center to celebrate the inauguration of the observatory and to test its newest structure starting from April 2018, says radio astronomer Fernando Camilo, chief scientist of the observatory. Typically, researchers take years for a new observatory to function properly and produce science with it. But with MeerKAT, they were amazed by how things went smoothly. "In a way it worked right from the start," says Camilo.

The bubbles could also solve an old enigma in radio astronomy. It is possible that the electrons that accelerate within them are the source of & # 39; filaments & # 39; luminous material tens of long parsecs extending from the galactic center, first seen in 1984. Larger bubbles have also been seen, which dominate those seen by MeerKAT as the part of the spectrum γ ray and could have a & # 39; similar origin.

The $ 4.4 billion MeerKAT ($ 330 million) is a series of 64 radio antennas, each 13.5 meters wide, at a remote site in the Northern Cape province. It will form the central core of the South African part of the SKA, which will be built in the 20's. The second section of the observatory will be in Australia.

This article is reproduced with permission and has been published for the first time 11 September 2019.

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