Study: Galaxies Die By Slow 'Strangulation'

Galaxies die due to by slow 'strangulations,' according to a new study. When they stop making stars, their death is usually a slow process that chokes them of the necessary cool gases over about four billion years.

In the study, researchers noted that dead galaxies showed high levels of metals, which build up during star formation and point to a slow strangulation process.

"Metals are a powerful tracer of the history of star formation: the more stars that are formed by a galaxy, the more metal content you'll see," said Dr Yingjie Peng from the University of Cambridge, the paper's lead author.

"So looking at levels of metals in dead galaxies should be able to tell us how they died."

Furthermore, study co-author Professor Robert Maiolino adds, "We found that for a given stellar mass, the metal content of a dead galaxy is significantly higher than a star-forming galaxy of similar mass. This isn't what we'd expect to see in the case of sudden gas removal, but it is consistent with the strangulation scenario."

Peng continues, "This is the first conclusive evidence that galaxies are being strangled to death. What's next though, is figuring out what's causing it. In essence, we know the cause of death, but we don't yet know who the murderer is, although there are a few suspects."

According to researchers the study can lend its methods to applications with galaxies that are very large in mass in order to answer yet more complex, but related, questions.

The study has been published in the journal Nature.