Signs in the Skies: Something Silent But Deadly Is Killing Galaxies
Across the universe, unsuspecting galaxies are literally getting the
life sucked out of them. Though the culprit is still at large, a
team of researchers
at the International Centre for Radio Astronomy Research (ICRAR) in
Western Australia is working tirelessly to crack the case—and to restore
law and order.
After examining 11,000 galaxies using the Sloan Digital Sky Survey
and Arecibo Legacy Fast ALFA survey, the team concluded that a process
called
ram-pressure stripping—which
forces gas out of galaxies—is more common than previously imagined.
It’s a quick death, because without gas, galaxies are unable to produce
more stars. The group’s findings were
published on January 17th in the
Monthly Notices of the Royal Astronomical Society.
So, who’s the prime suspect in this crime? It’s none other than
dark matter:
the mysterious, invisible material thought to make up 27 percent of the
universe. Turns out, it’s also quite the smooth criminal.
“During their lifetimes, galaxies can inhabit [dark matter] halos of
different sizes, ranging from masses typical of our own Milky Way to
halos thousands of times more massive,” Toby Brown, the lead author of
the study and a PhD candidate at ICRAR,
said in a press release.
“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.”
The team’s research suggests that not only is ram-pressure stripping
pretty common, it can happen to small and large galactic groups alike.
“This paper demonstrates that the same process is operating in much
smaller groups of just a few galaxies together with much less dark
matter,” Brown said. “Most galaxies in the universe live in these groups
of between two and a hundred galaxies.”
It’s a tragic tale, but it could be worse: some galaxies get
strangled to death. It’s a cold universe out there, but no one said the final frontier was for the faint of heart.
For video:
http://gizmodo.com/something-silent-but-deadly-is-killing-galaxies-1791328049
