Strange bubbles at the heart of our galaxy have been puzzling scientists for 15 years. Now they may have found the answe

Chris Lintott

Published: April 20, 2025 at 1:01 am

Fifteen years ago, astronomers looking through data from the Fermi Gamma-ray Space Telescope noticed odd bubbles that extended above and below the Milky Way’s disc.

Stretching tens of thousands of lightyears across and apparently centred on the Galactic centre, these features were recently joined by larger ‘superbubbles’, spotted in the data obtained by the eROSITA X-ray satellite.

But what are they?



An all-sky map showing the centre of our Milky Way galaxy in x-ray, captured by the eROSITA
X-ray telescope onboard the Spektrum-Roentgen-Gamma (SRG) observatory. Credit: MPE/IKI


The fact that they seem to be aligned with the Galactic centre suggests the supermassive black hole that lurks there – or the activity that happens when material accretes onto it – might be responsible. But there isn’t enough energy being pumped into the Galaxy today from this source to get anywhere close to what’s needed.

Any explanation needs to account for both energetic gamma-ray bubbles and the larger X-ray features.

Most attempts at an explanation assume that, in the recent past, the black hole at the centre of the Galaxy was growing rapidly.

If so, the Milky Way would have resembled nearby galaxies that have active galactic nuclei surrounded by a hot accretion disc and powering jets of rapidly moving material stretching out into the Galaxy.

More:
https://www.skyatnightmagazine.com/news/fermi-erosita-bubbles