'Fermi’s deadly secret': The invisible shockwave still expanding in our galaxy

Produced by: Mohsin Shaikh

Bubble Mystery

Two massive, high-energy bubbles towering over the Milky Way were first detected in 2010. These colossal structures, extending 50,000 light-years, puzzled astronomers for over a decade, hinting at an ancient explosion in our galaxy’s core.

Representative pic/NASA

X-ray Proof

In 2020, the eRosita telescope revealed even larger X-ray bubbles, nearly doubling the size of the Fermi Bubbles. This unexpected discovery suggested a cataclysmic event that expelled enormous amounts of energy millions of years ago.

Credit: Flickr/DLR (CC-BY 3.0)

Black Hole

A new University of Michigan study confirms that Sagittarius A*, our galaxy’s supermassive black hole, caused this explosion. It unleashed a jet of cosmic rays and X-ray radiation, reshaping the space around the Milky Way’s center.

Representative pic

Violent Outburst

This eruption, classified as an Active Galactic Nucleus event, occurred 2.6 million years ago. According to astrophysicist Mateusz Ruszkowski, such bursts are key to controlling how black holes grow within their host galaxies.

Representative pic

100,000 Years

Simulations show the explosion lasted around 100,000 years—a blink in cosmic time. Astrophysicist Ellen Zweibel’s research suggests that the burst’s peak energy output was concentrated into just one percent of this time frame.

Credit: University of Wisconsin–Madison

Cosmic Rays

The event blasted charged particles deep into space, forming the Fermi Bubbles. These cosmic rays continue expanding, revealing how black holes can expel energy across vast distances rather than simply consuming matter.

Credit: NASA

Milky Way’s Past

This discovery rewrites our galaxy’s history. Far from being a dormant black hole, Sagittarius A* was once an active force, shaping the Milky Way’s structure with an immense, rapid-energy injection.

Future Eruption

If it happened before, it can happen again. Scientists warn that if Sagittarius A* absorbs enough gas or a passing star, it could trigger another outburst, possibly forming new energy bubbles in the future.

Representative pic

Universal Pattern

Other galaxies show similar bubble-like structures, suggesting that supermassive black holes frequently reshape their surroundings. This means the Milky Way’s violent past is not unique—it’s part of a cosmic cycle.

Representative pic/NASA