Scientists thought the Milky Way and Andromeda galaxies were unique: They’ve got rings of smaller dwarf galaxies orbiting in what seems to be a synchronized fashion. But when a team of scientists recently looked at another galaxy, they realized it also seemed to shepherd a flock of dwarfs in a strange, synchronized dance. That’s not supposed to happen.
An international team of four researchers noticed the behavior in the elliptical Centaurus A galaxy, 30 million light years away from our own Milky Way. Dwarf galaxies should travel randomly around their parent, based on the standard theory of how galaxies form. Seeing yet another galaxy with this strange behavior is highly unlikely, and calls into question the very model that scientists use to understand structure in our universe.
Sure, you would expect to find one galaxy with this behavior, study author Oliver Müller from the University of Basel in Switzerland told Gizmodo. “But two or three is startling.”
“There should be pure chaos and not order,” said Müller. “To find everywhere we look this extreme order where we expect disorder—this is strange.”
The model physicists use to account for the universe’s behavior since the Big Bang is called the “lambda-CDM” model. It’s basically just a summary of what we know about the universe: It started with a bang, it contains galaxies in a vast cosmic web with voids in between, it has strange substances called dark matter and dark energy, it’s expanding, and that expansion is accelerating. The model predicts that during formation, dwarf galaxies should both appear and move randomly around their host galaxies.
Our home galaxy, the Milky Way, and Andromeda have both thrown a wrench in that model, with disks of dwarf galaxies orbiting them sort of like Saturn’s rings. Perhaps these two galaxies were outliers, thought some. Or maybe there’s something strange about our “Local Group” of galaxies, which contains Milky Way and Andromeda.
The researchers used data from a survey of galaxies taken by the Parkes Telescope in Australia to look at Centaurus A, which is not a member of the Local Group. Its disk of dwarf galaxies is oriented to us head-on, so the researchers could use the Doppler effect to see the light from 14 dwarf galaxies stretched on one side of Centaurus and scrunched on the other. In other words, it looked like the dwarf galaxies were moving away from us on one side and towards us on the other, like a spinning disk.
Basically, scientists expected that Centaurus A would have randomly assorted dwarf galaxies, but instead, it appeared to have a ring of co-moving galaxies like our own, against the assumptions of the popular standard theory of the universe. The odds are around one in a thousand that a single galaxy would have a disk of coordinated dwarf galaxies like this. The odds that three galaxies would are a whole lot lower—unless our theory of galaxy formation is wrong.
This probably doesn’t throw a wrench in our theory of dark matter, which accounts for a lot of the mysterious gravitational movements we see in space, said Müller. “But I will say that it’s a challenge to the standard way we think about the formation of these groups.”
The researchers published their story today in the journal Science.
- Ryan F. Mandelbaum
My Take:
“There should be pure chaos and not order,” said Müller. “To find everywhere we look this extreme order where we expect disorder—this is strange.”
On the weight of these heavy words you will not hear a laugh....all except inside the Gates of Eden.
Thanks Bob D.
My Take:
“There should be pure chaos and not order,” said Müller. “To find everywhere we look this extreme order where we expect disorder—this is strange.”
On the weight of these heavy words you will not hear a laugh....all except inside the Gates of Eden.
Thanks Bob D.
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