Newfound structures hint at a violent past for the galaxy’s heart

Quote Originally Posted by Science News
Discoveries keep bubbling up at the center of the Milky Way.

Colossal bubbles emanate from this spot, spitting out radio waves detected with the help of a new telescope. The structures are a sign of a long-ago burst of activity from the region around the now relatively sleepy supermassive black hole at the galaxy’s center, researchers report in the Sept. 12 Nature.

An image of the ethereal bubbles showcases the capabilities of the South African Radio Astronomy Observatory’s MeerKAT radio telescope, an array of 64 dishes spread out over a region eight kilometers across near Carnarvon. The completed telescope began taking data in spring 2018.

These radio wave–emitting bubbles extend hundreds of light-years above and below the plane of the Milky Way. And they point to “something extraordinary that had happened in the galactic center,” says astrophysicist Ian Heywood of the University of Oxford.

Heywood and colleagues estimate that an event involving vast amounts of energy — equivalent to the explosion of approximately 100 stars — sent matter spewing out of the region around the black hole a few million years ago. Speedy, electrically charged particles produced in that event, accelerated by magnetic fields, create the bubbles’ radio waves, the team suggests.

A temporary black hole feeding frenzy long ago could have spawned the bubbles, as the behemoth gulped down matter and spewed the excess outward. Or the bubbles might be the result of a mob of stars forming around the black hole. Those stars could have eventually exploded in supernovas, expelling their innards.