The bubbles are just visible as the smoky smudges above and below the bright central line of the galaxy South African Radio Astronomy Observatory

The centre of our galaxy has blown some bubbles. Astronomers using the MeerKAT telescope in South Africa have discovered a pair of enormous bubbles of high-energy particles looming hundreds of light years above and below the Milky Way’s central supermassive black hole.

MeerKAT is sensitive to a type of radio wave called synchrotron radiation, which is caused by charged particles like electrons moving near the speed of light. Farhad Zadeh at Northwestern University in Illinois and his colleagues used this radiation to map the area near the centre of our galaxy.

They found a two huge bubbles protruding out from the area around the supermassive black hole at the centre of the galaxy, perpendicular to the galaxy’s disk. These balloons of particles must have been accelerated to their high speeds by the some extraordinarily powerful event at the middle of the Milky Way.


“What the event was is the million-dollar question,” says Zadeh. There are two main ideas: the black hole could have become briefly active, gobbling up lots of material at once and causing a huge flare, or a burst of star formation could have blasted extra energy through the galactic centre.

While we don’t know what caused the bubbles, they may have helped solve a cosmic mystery. More than 100 strange filaments of magnetized particles were discovered near the centre of the galaxy about 35 years ago, and we don’t know how they formed or why they have enough energy to emit radio waves despite not being clearly associated with any energetic objects.

The bubbles are circled here South African Radio Astronomy Observatory

The researchers found that almost all of these bright strands are inside the bubbles. Because of the remarkable alignment, it’s possible that the same powerful blast that created the bubbles also gave the weird filaments the energy to light up.

“These events are shaping the evolution of the nucleus of our own galaxy,” says Zadeh. “By learning about our own galaxy we can learn more about other, more active, galaxies that are too far away to study in detail.”

Journal reference: Nature, DOI: 10.1038/s41586-019-1532-5