Giant Radio ‘Bubbles’ Spotted in Center of Milky Way

The plane of the Milky Way galaxy in this radio image is marked by exploded stars and regions where new stars are being born. Magnetized filaments can be seen running parallel to the bubbles which extend vertically above and below the plane of the galaxy. (Image courtesy of MeerKAT)

(CN) – An hourglass-shaped structure stretching hundreds of light-years above and below the center of the Milky Way is one of the largest formations ever observed in our galaxy, an international team of astronomers said in a study released Wednesday.

The structure – composed of twin “bubbles” that are hundreds of light-years tall – towers over other objects in the central region of the galaxy, according to the study published in the journal Nature.

Scientists said the radio-emitting formation was likely produced by a powerful energy explosion that occurred near the galaxy’s super massive black hole millions of years ago.

Oxford University researcher and study lead author Ian Heywood said in a statement that the Milky Way is comparatively calmer than other galaxies that have “very active” black holes at their center.

“Even so, the Milky Way’s central black hole can from time to time become uncharacteristically active, flaring up as it periodically devours massive clumps of dust and gas,” Heywood said. “It’s possible that one such feeding frenzy triggered powerful outbursts that inflated this previously unseen feature.”

To observe the structure, which is hidden from view behind a dense cloud of dust in the center of the galaxy, the team utilized the MeerKAT – originally the Karoo Array Telescope – a radio telescope consisting of 64 antennas spread across the Northern Cape of South Africa.

Northwestern University scientist Yusef Zadeh, who has studied volatile activity at our galaxy’s center for decades, said in the statement that the discovery illuminates “highly organized magnetic filaments” in the Milky Way’s center that he discovered in the 1980s.

“The radio bubbles discovered with MeerKAT now shed light on the origin of the filaments,” Zadeh said. “Almost all of the more than 100 filaments are confined by the radio bubbles.”

Researchers believe that the energy eruption that shaped the bubble-like structures – located 25,000 light-years from Earth – are closely related to an acceleration of electrons required for the formation’s radio-emitting qualities.

Scientists used a process known as synchrotron radiation – in which fast-moving electrons are shot into space to penetrate the magnetic fields in the galaxy’s cloudy center – to map out a radio signal of the formation.

The radio light produced by this observation is easily seen by MeerKAT, researchers said.

Fernando Camilo of the South African Radio Astronomy Observatory said in the statement that the twin bubbles were previously hidden from view because of the bright glare from radio light.

“Teasing out the bubbles from the background noise was a technical tour de force, only made possible by MeerKAT’s unique characteristics and ideal location,” Camilo said. “With this unexpected discovery we’re witnessing in the Milky Way a novel manifestation of galaxy-scale outflows of matter and energy, ultimately governed by the central black hole.”

The study was supported by South Africa’s National Research Foundation and the National Science Foundation.

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