Do the Milky Way's companions spell trouble for dark matter?

Do the Milky Way’s companions spell trouble for dark matter?
The galaxy pair UGC 9618 / VV 340, two spiral galaxies at the beginning of a collision. Credit: NASA, ESA, the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration, and A. Evans. Credit: University of Virginia, Charlottesville/NRAO/Stony Brook University

( -- Astronomers from the University of Bonn in Germany have discovered a vast structure of satellite galaxies and clusters of stars surrounding our Galaxy, stretching out across a million light years. The work challenges the existence of dark matter, part of the standard model for the evolution of the universe. PhD student and lead author Marcel Pawlowski reports the team’s findings in a paper in the journal Monthly Notices of the Royal Astronomical Society.

The Milky Way, the galaxy we live in, consists of around three hundred thousand million stars as well as large amounts of gas and dust arranged with arms in a flat disk that wind out from a central bar. The diameter of the main part of the Milky Way is about 100,000 , meaning that a beam of light takes 100,000 years to travel across it. A number of smaller satellite and spherical clusters of stars (so-called globular clusters) orbit at various distances from the main Galaxy.

Conventional models for the origin and evolution of the universe (cosmology) are based on the presence of ‘dark matter’, invisible material thought to make up about 23% of the content of the cosmos that has never been detected directly. In this model, the Milky Way is predicted to have far more satellite galaxies than are actually seen.

In their effort to understand exactly what surrounds our Galaxy, the scientists used a range of sources from twentieth century photographic plates to images from the robotic telescope of the Sloan Deep Sky Survey. Using all these data they assembled a picture that includes bright ‘classical’ satellite galaxies, more recently detected fainter satellites and the younger globular clusters.

Do the Milky Way’s companions spell trouble for dark matter?
A galaxy gets torn apart in a collision. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

“Once we had completed our analysis, a new picture of our cosmic neighborhood emerged”, says Pawlowski. The found that all the different objects are distributed in a plane at right angles to the galactic disk. The newly-discovered structure is huge, extending from as close as 33,000 light years to as far away as one million light years from the centre of the Galaxy.

Team member Pavel Kroupa, professor for astronomy at the University of Bonn, adds “We were baffled by how well the distributions of the different types of objects agreed with each other”. As the different companions move around the Milky Way, they lose material, stars and sometimes gas, which forms long streams along their paths. The new results show that this lost material is aligned with the plane of galaxies and clusters too. “This illustrates that the objects are not only situated within this plane right now, but that they move within it”, says Pawlowski. “The structure is stable.”

The various dark matter models struggle to explain this arrangement. “In the standard theories, the satellite galaxies would have formed as individual objects before being captured by the Milky Way”, explains Kroupa. “As they would have come from many directions, it is next to impossible for them to end up distributed in such a thin plane structure.”

Postdoctoral researcher and team member Jan Pflamm-Altenburg suggests an alternative explanation. “The satellite galaxies and clusters must have formed together in one major event, a collision of two galaxies.” Such collisions are relatively common and lead to large chunks of galaxies being torn out due to gravitational and tidal forces acting on the stars, gas and dust they contain, forming tails that are the birthplaces of new objects like star clusters and dwarf galaxies.

Pawlowski adds, “We think that the Milky Way collided with another galaxy in the distant past. The other galaxy lost part of its material, material that then formed our Galaxy’s and the younger globular clusters and the bulge at the galactic centre. The companions we see today are the debris of this 11 billion year old collision.”

Kroupa concludes by highlighting the wider significance of the new work. “Our model appears to rule out the presence of in the universe, threatening a central pillar of current cosmological theory. We see this as the beginning of a paradigm shift, one that will ultimately lead us to a new understanding of the universe we inhabit.”

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More information: The work appears in "The VPOS: a vast polar structure of satellite galaxies, globular clusters and streams around the Milky Way", M. S. Pawlowski, et al. Monthly Notices of the Royal Astronomical Society, in press. A preprint of the paper can be downloaded from
Citation: Do the Milky Way's companions spell trouble for dark matter? (2012, April 25) retrieved 21 August 2019 from
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Apr 25, 2012
The presence of both globular clusters and hypervelocity stars lying within a preferred plane of the Milky Way also support the notion of galactic growth from ejection rather than growth from condensation.

LaViolette's continuous creation model supports this scenario. He has already commented on this notion.


Apr 25, 2012
Theorists make a big mistake when they imagine that they can fix the problems of cosmology with little bandaids. Cosmology is extremely uncertain. Parallax only works to 1% the diameter of the Milky Way!

This makes cosmology, as a discipline, unique from other disciplines, insofar as we must be that much more willing to question assumptions and contemplate alternatives which seem "radical" to us, if we are to make any progress. Ideational fluency is absolutely critical to such endeavors: We must actively cultivate an interest in competing ideas in cosmology, if there is to be any tangible progress. There is no sense to merely trying to prove the initial hypotheses which we conjure. We have to push ourselves to look beyond our preferences and prejudices.

This notion that mechanical processes - like galactic collisions - are the solution to what we see is a band-aid. It's not a creative solution. There is a much stronger force out there -- the electric force.

Apr 25, 2012
Once again the proof is in the pudding, we see the invisible 23% "Dark Fudge" model for what it is full of.

LaViolette, hum, hockey player, hockey stick , Al Gore, the Triliteral Commision.... Consipracy?
My tiny divining rod is stirring in my underpants, I think I'm getting a Clue (thank you Hardly Boys), must have a conference with my Kuato (what do you call yours)

Tenser, said the Tensor, Neutron Repulsion, Neutron Composition, Neutron Revulsion have begun


Apr 25, 2012
The geometry of the Birkeland Current is very important. When you have two separate plasma filaments, the force between them is the electric force. And yet, they do not combine. There remains a short-range repulsion. This geometry extends the electric force to infinite distances. To get there, all that's required is to fix the MHD models to reflect the tiny resistance necessary to support an E-field within the plasma, as is observed within the laboratory.

With that done, then double layers permit the creation of complex electrodynamic structures out of nothing more than plasma. We know from the ionosphere that we can have plus and minus right next to each other, without recombination.

The thin plates we see with galaxies are suggestive, within this context, of a Faraday disc. Marklund convection can explain the sorting of the elements within the galactic structure. A z-pinch explains the ion sump action. Ions are drawn in through the disc from surrounding space, along arms.

Apr 25, 2012
before anyone asks -- please note that this is an article about a piece of British science. So three hundred thousand million is the best way to represent three hundred billion.

Why- well because there are two systems of numbering called long and short 1 billion in the long system is equal to 1 trillion in the short system ( used in in the good ole USA)

I have seen this question appear twenty times and i have never seen someone put the correct answer.

Apr 25, 2012
I thought it was already well accepted that the milky way had collided with another galaxy.

Maybe it was just something on television but doesn't the path of sol through the galaxy extremely odd, as it is independent of any arm and is not gravitationally synced with anything else and travels in a huge elliptic around the core.

Apr 25, 2012
Why not just use 10¹² This is after all a scientificy journal so why not use SI units .I think the editors overshoot the dumbing down and anyway if people can understand baseball and even cricket sports then they can understand SI terminology like Kelvin ,Meters Kg and so on easily

Apr 25, 2012
It appears "dark" matter is gaining "luminousity" - in almost direct correlation to our own technical ability to see (therefore understand) it.

Apr 25, 2012
How would a collision produce such a structured plane at 90 degrees? Wouldn't a collision still produce random directions of material?

Apr 25, 2012
Do other galaxys also have this behavior which lead Fritz(Crazy man)Zwicky to say "What we see is not enough" ? . I think the answer is yes ,Correct me if I'm wrong
However this article is just BAD journalism ,piggy backing on the other "Serious Blow to DM ,,,,, " something like that story ,example ' "(so-called globular clusters) " ,well they are so called because they are bunched together like a big glob just like a bunch of individuals or a mob
It's a detective story and not necessarily a scientifically one per say and who's to say that the originators of these papers aren't just as crazy as Fritz Zwicky ?

Apr 25, 2012
Dark Matter, permeating space,
Why can't they find a trace of you?
O curve faker, you heart breaker,
Wherever they find you they can't find you too!
Weak wimpers or gravity that's weird,
The universe seems geared to you,
Your clowning the physicist's world,
In confusion they are hurled,
Dark matter and me!

Apr 26, 2012
I think it was Germany and Britain who used the long system, which I preferred because it maintained the basic number steps, i.e. 1, 10, 100, 1,000, 10,000, 100,000, and 1,000,000.
Which then followed with 1,000,000, 10,000,000, 100,000,000, 1,000,000,000, 10,000,000,000, 100,000,000,000 then finally 1,000,000,000,000 (One Billion).
But over time the short system won out.
The short system aborts this.

Apr 27, 2012
...explains Kroupa. As they would have come from many directions, it is next to impossible for them to end up distributed in such a thin plane structure.

And yet observations do not fit this "impossibility". This is why putting absolute faith into theories can be detrimental, there is no room left for the plausible that is observations.

Apr 29, 2012
How would a collision produce such a structured plane at 90 degrees? Wouldn't a collision still produce random directions of material?

Depends on the type of collision, and the rotation of the individual galaxies.

Was it a head-on collision? A T-bone collision? And which way were the disk(s) oriented with respect to the galaxies' approach vectors?

The satellite galaxies and clusters must have formed together in one major event,


a collision of two galaxies.

Not necessarily. That's a fallacy.

It could have been that way, more or less, from the beginning of the universe.

The Milky Way, the galaxy we live in, consists of around three hundred thousand million stars as well as large amounts of gas and dust


Depending on who's data you use, the margin of error in counting the number of stars in the Milky Way is as large or larger than the alleged missing mass of Dark Matter anyway.

According to Wiki, the galaxy has a trillion solar masses.

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