The Giant Fermi Bubbles in the Milky Way

Enormous expanding bubbles of ultra-powerful gamma rays, each centered on nothingness, meet at our galaxy’s core, as depicted in this illustration of the Milky Way. Discovered in 2010, the origin of these bubbles remains a complete mystery.

In November 2010, astronomers using NASA’s Fermi Gamma-ray Space Telescope announced an astonishing discovery. Emanating from the center of our Milky Way Galaxy are two bubbles made solely of powerful gamma rays.

Compared to other galaxies, the Milky Way is relatively peaceful. Even the center of our galaxy, where things are the most tumultuous, experiences relatively few violent events. Unlike in other galaxies, the black hole at the center of the Milky Way doesn't ravenously suck in huge meals of gas or spit out enormous jets of radiation and light. But our galaxy wasn't always so sleepy. In 2010, a team of scientists working at the Harvard-Smithsonian Center for Astrophysics discovered a pair of "Fermi bubbles" extending tens of thousands of light-years above and below the Milky Way's disk. Those enormous balloons are the remnants of an ancient cataclysm, a powerful event that took place millions of years ago, when the black hole at the center of our galaxy feasted on an enormous amount of gas and dust in amounts that perhaps reached several hundreds or even thousands of times the mass of the sun. But exactly how the bubbles formed, and what they can tell us about the history of our galaxy, remains a mystery.

Three astrophysicists who discovered the Fermi bubbles recently spoke with The Kavli Foundation about ongoing attempts to understand the cause and implications of these unexpected and strange structures, as well as the ways in which they may help in the hunt for dark matter .