Exactly how the gas has been ejected is still a mystery, but the research team, including Professor Naomi McClure-Griffiths from the Australian National University (ANU), said their findings could have important implications for the future of our galaxy.
The study also raises new questions about what's happening in our galactic centre right now.
Professor McClure-Griffiths explained, "Galaxies can be really good at shooting themselves in the foot. When you drive out a lot of mass, you're losing some of the material that could be used to form stars, and if you lose enough of it, the galaxy can't form stars at all anymore."
The centre of the Milky Way is home to a massive black hole, but it's unclear whether this black hole has expelled the gas, or whether it was blown by the thousands of massive stars at the centre of the galaxy.
"The wind at the centre of the Milky Way has been the topic of plenty of debate since the discovery a decade ago of the so-called Fermi bubbles – two giant orbs filled with hot gas and cosmic rays. We've observed there's not only hot gas coming from the centre of our galaxy, but also cold and very dense gas," Professor McClure-Griffiths added.
Lead author Dr Enrico Di Teodoro from Johns Hopkins University added, "We don't know how either the black hole or the star formation can produce this phenomenon. We're still looking for the smoking gun, but it gets more complicated the more we learn about it.
"This is the first time something like this has been observed in our galaxy. We see these kind of processes happening in other galaxies. But, with external galaxies you get much more massive black holes, star formation activity is higher, it makes it easier for the galaxy to expel material."
Dr Di Teodoro said, "Our own galaxy is almost like a laboratory that we can actually get into and try to understand how things work by looking at them up close."
The gas was observed using the Atacama Pathfinder EXperiment (APEX) operated by the European Southern Observatory (ESO) in Chile.
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