Death is one of the grand inevitabilities of the universe, even for galaxies. Just like living things they come into existence, grow larger, and sometimes, their bright lights are snuffed out.
Now researchers know why many galaxies bite the interstellar dust. In a paper recently published in the Monthly Notices of the Royal Astronomical Society, researchers concluded that one of the leading causes of galaxy death was a process called ram-pressure stripping.
Galaxies like these can perish at the hands of dark matter. Credit: ICRAR, NASA, ESA, the Hubble Heritage Team (STScI/AURA)
“You can think of it like a giant cosmic broom that comes through and physically sweeps the gas from the galaxies.” Toby Brown, lead author of the paper said.
Since gasses are a critical nutrient for growing baby stars, their absence starves the galaxies from within. “If you remove the fuel for star formation then you effectively kill the galaxy and turn it into a dead object,” Brown added.
Who is the particular culprit of this vile galactic crime? Scientists think that dark matter is to blame. Or, more specifically, dark matter halos, which are areas of dark matter that surround galaxies. When a galaxy—making its merry way through the universe—encounters a larger area of dark matter, the interaction (ram-pressure stripping) can strip away the galaxy’s gasses, leaving it without the means to thrive.
This galaxy, located in the Virgo Supercluster is believed to be a victim of ram-pressure stripping, a process that kills galaxies. Credit: H.Crowl (Yale University) and WIYN/NOAO/AURA/NSF
Researchers have observed ram-pressure stripping in galaxies for many years now. From our perspective on Earth, stripped galaxies look windswept, elongated in the direction of the gasses that were stripped from them. But until now, the galaxies that had suffered this fate were all in clusters or areas where galaxies were located close together.
In the new study, Brown and colleagues show that the phenomenon is much more widespread, occurring not only in tightly-packed clusters of galaxies but also in more spread out groups of galaxies, which helps researchers gain a better understanding of a galaxy’s life cycle.
In the end, it looks like even galaxies can be blown away.