About 7 million years ago, something exploded in the heart of our galaxy.
The cataclysmic event was so fierce that it drilled two holes in the interstellar space and carved out two colossal bubbles tied together in an hourglass over light years. From the structure a stream of radio waves streamed through the cosmos like SOS signals – and in the spring of 2018 a team of astronomers took them.
It's still unclear what happened exactly all those years ago, the researchers report this week in the journal Nature. But study author Ian Heywood, an astrophysicist at Oxford University, is confident that it was "something out of the ordinary," reports Emily Conover of Science News .
The observation of the team was made possible by the South African The MeerKAT telescope of the Radio Astronomical Observatory, which began data collection in the spring of 201
The nature of this violent affair remains mysterious, but the team thinks that there are a few possible explanations. In one case, the supermassive Black Hole of the Milky Way quickly devoured a huge matter buffet and spewed some of the surplus out into space.
Another possibility is that the radio waves were generated by a "starburst", the almost simultaneous birth of about 100 short-lived stars, which exploded as a supernova after a few million years. The combined force of this living, swift, young event, which other observations pointed out, might have been enough to blow gaseous bubbles into the galactic center.
In both modes of warfare, the catastrophe spewed on a tremendous amount of matter. The space around it forged two bubbles filled with hot gas – and it seems they've been expanding ever since.
Will the couple eventually pop? Not exactly. "Within a few million years [the bubbles will]they are likely to dissolve to a point where they can no longer be distinguished from the background radio emission from the central regions of the galaxy," study author Fernando Camilo Hannah Osborne said at Newsweek .
Capturing the bubbles in their present form, researchers may be on their way to solving another puzzle that has occupied astronomers since the 1980s. More than three decades ago, scientists in the same region discovered a series of long, narrow, radio-emitting stripes – but their cause could not be explained. The proximity of the two structures suggests that they have a common history.
When Jun-Hui Zhao, an astronomer at the Harvard-Smithsonian Center for Astrophysics who was not involved in the study, Conover said, this new observation helps put the "mosaic" in the middle of the Milky Way together.