Discoveries bubble up in the middle of the Milky Way.
Colossal bubbles come from this location and spit out radio waves detected with the help of a new telescope. The structures are a sign of a long time ago activity from the region exploded around the now relatively sleepy supermassive black hole in the center of the galaxy, researchers report in September 12 Nature .
An image of the ethereal bubbles shows the capacity of South African Radio Astronomy Observatory's MeerKAT radio telescope, a matrix of 64 dishes spread over a region eight miles above Carnarvon. The completed telescope began to take data in the spring of 2018.
These radio-wave bubbles extend hundreds of light years above and below the Milky Way. And they point to "something unusual that had happened in the galactic center," says astrophysicist Ian Heywood of the University of Oxford.
Heywood and colleagues estimate that an event involving huge amounts of energy – equivalent to the explosion of about 100 stars – sent matter spewing out of the black hole region a few million years ago. Rapid, electrically charged particles produced in this event, accelerated by magnetic fields, create the bubbles radio waves, the team suggests.
A temporary black hole that had eaten frenzy a long time ago could have given the bubbles, when the beetle gulped down the matter and sprayed the excess outward. Or the bubbles may be the result of a mass of stars forming around the black hole. These stars could eventually explode into supernovae and expel their interiors.
The bubbles are brighter along their edges, suggesting that a shock wave of material plows outward, the researchers found. This means that everything that produced the bubbles was not an ongoing process, but one that was activated after a quiet period.
These radio bubbles are "a piece of the mosaic" in the center of the galaxy, says astrophysicist Jun-Hui Zhao of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., Who was not involved in the discovery. In March, astronomers reported chimneys of X-rays spewing from the heart of the galaxy ( SN: 3/20/19 ). These chimneys overlap with the recently discovered radio structures, suggesting a common origin. And previous observations revealed huge gamma-ray bubbles, much larger than the X-ray and radio structures, that balloon from either side of the galaxy ( SN: 11/9/10 ).
Glimpsing new pieces of the mosaic, such as radio bubbles, can help researchers determine the origin of some of the previously discovered oddities. For example, the bubbles enclose a set of mysterious structures known as radio filaments, high, thin stripes discovered in the 1980s. Although it is still unclear how the filaments are formed, the new result links them to the radio bubbles.
"This is really the first time you see the clear connection between the outflows and the illumination of these filaments," says astronomer Daniel Wang of the University of Massachusetts Amherst who was not involved in the research. "This is a great image."