Thousands of galaxies are seeing their star stuff stripped away quick, fast and in a hurry. Astronomically speaking. Galaxies go from living ordinary lives to being stripped of its star-making gas in just tens of millions of years.
What’s happening? It’s called ram-pressure stripping and it’s a much more common process than researchers first thought. Researchers from the International Centre for Radio Astronomy Research, or ICRAR, conducted a study of 11,000 galaxies whose gas were being stripped away.
What’s the driving force behind ram-pressure stripping? Everyone’s favorite elusive matter, dark matter. We can’t see it, but researchers say it makes up just over a quarter of the matter in our Universe.
Did You Know: The most common process for galaxies to run out of gas is called strangulation. Galaxies churn out stars quicker than the gas can be replenished. They end up starving themselves to death.
Picture each galaxy nestled within clouds of dark matter called dark matter halos. Toby Brown, who led the study, explains it from here. “During their lifetimes, galaxies can inhabit halos of different sizes, ranging from masses typical of our own Milky Way to halos thousands of times more massive,” Brown says.
“As galaxies fall through these larger halos, the superheated intergalactic plasma between them removes their gas in a fast-acting process called ram-pressure stripping.”
Ram-pressure stripping isn’t a new discovery. Researchers see it happen in galaxy clusters. But this study shows the same process is killing off much smaller clusters of galaxies. “Most galaxies in the Universe live in these groups of between two and a hundred galaxies,” Brown explains.
Researchers liken ram-pressure stripping to a “giant cosmic broom,” sweeping the lifeblood of galaxies away. Here’s a video animation showing how the gas is pushed away from its home galaxy.