New Study Finds Clumps and Streams of Dark Matter in the Milky Way

by Nancy Atkinson on August 6, 2008

The Bullet Cluster. Credit: NASA

The Bullet Cluster. Credit: NASA


One of the leading theories for how the universe evolved after the Big Bang is the Cold Dark Matter Theory (CDM). This theory proposes that chilly dark matter moved slowly in the early universe, allowing matter to clump together to form the clusters of galaxies that we see, instead of matter being distributed evenly across the universe. Using the properties of the CDM theory, astronomers recently ran an intensive computer program using one of the world’s most powerful supercomputers to simulate the halo of dark matter that envelopes our galaxy. The simulation revealed dense clumps and streams of the mysterious dark matter lurking within our Milky Way galaxy, including the region of our solar system.

“In previous simulations, this region came out smooth, but now we have enough detail to see clumps of dark matter,” said Piero Madau, professor of astronomy and astrophysics at the University of California, Santa Cruz.

This simulation, detailed in an article in the journal Nature, may help may help scientists figure out what dark matter actually is. So far, it has been detected only through its gravitational effects on stars and galaxies. Another part of the CDM theory says that dark matter consists of weakly interacting massive particles (WIMPs), which can annihilate each other and emit gamma rays when they collide. Gamma rays from dark matter annihilation could be detected by the recently launched Gamma-ray Large Area Space Telescope (GLAST).

“That’s what makes this exciting,” Madau said. “Some of those clumps are so dense they will emit a lot of gamma rays if there is dark matter annihilation, and it might easily be detected by GLAST.”

If so, it would be the first direct detection of WIMPS.

Although the nature of dark matter remains a mystery, it appears to account for about 82 percent of the matter in the universe. The clumps of dark matter created “gravitational well” that draws in ordinary matter, giving rise to galaxies in the centers of dark matter halos.

Using the Jaguar supercomputer at Oak Ridge National Laboratory, the simulation took about one month to run and simulated the distribution of dark matter from for 13.7 billion years – from near the time of the Big Bang until the current epoch. Running on up to 3,000 processors in parallel, the computations used about 1.1 million processor-hours.

Source: PhysOrg

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  • neoguru

    Add my name to those expressing concern that sumulated results are often stated in headlines as factual. The practice is very common and misleading. However, it was an interesting article.

  • Peter K

    I’m with neoguru. And please people, realize that we have to do the best we can with the data at hand. If those early map makers hadn’t honed their craft with inaccurate drawings, many would not have had the courage to pit ship against waves. We have to start somewhere but by your logic, we should all stare at our navels as we’re really not that sure about anything else!
    In this day and age of information, we can explore the universe with more than ships and telescopes.

  • Dark Gnat

    From the outside looking in, it’s easy to criticize and call the efforts of others a waste of time.

    Strangely, none of the critics have anything better to offer.

    If dark matter theory is wrong, then it’s wrong. But in order to know whether it is wrong, scientific method has to be applied.

    By doing these simulations, researchers can get a better idea of what to look for in reality. If they find it, great, if not, then theories are revised.

    That is how it works. There is no failure as long as something is learned.

    The greatest minds of history were almost always ridiculed by their peers, often because their peers simply didn’t like the ideas presented by those great minds.

    It is better to search for years and be wrong, than to never search at all.

  • Astrofreak

    Utter nonsense once again. So, somebody wrote a “simulation” purporting to analyze something we don’t know much of anything about, they then “ran” their simulation and now we have more “evidence/proof/indications of” whatever.
    Thanks for the waste of bytes.

  • Dark Gnat

    Yeah, simulations are bad. Flight simulators, CAD, and anything that uses computers to model reality or theory is bad.

    In fact, maybe thought experiments and theoretical mathmatics should be abolished, because they are all a waste of time too.

    Maybe we should shut down all IR, UV and X-ray telescopes, because we can only see optical light, and the other stuff isn’t really there, because we can’t directly see it.

  • DrNecropolis

    Personally I believe computer modeling and simulations are some of the most useful tools in our scientific arsenal. That is of course assuming that you are building your sim from the bottom up, that is your end assumptions aren’t built into your models design. As long as you understand the limitations of your model it can be extremely helpful, just don’t run around saying , “Well my model proved it so it must be true”, that’s just plain irresponsible.

  • John Mendenhall

    Quote from Neoguru:
    “Add my name to those expressing concern that sumulated results are often stated in headlines as factual. The practice is very common and misleading. However, it was an interesting article.”

    Good summary of something seen all too often, even here on BAUT. Add my name, too.

  • curtis

    better than 80% of the Universe’ mass is “dark matter”. Dark matter has had the definition of “non-baryonic” matter, or to the laymen, matter we cannot observe directly. Not a good way of puting it, since baryonic matter can still be dark. it is only visible if it either emits it’s own light, or reflects light from an emitting source.

    My biggest question is why the assumption that this is non-baryonic? We call it dark matter because we cannot see it, but know it is there based on it’s gravitational effects. Could it in fact be baryonic matter that is too small / distant to observe directly. Every day we learn that space is not the empty vacuum we once thought. Thousands of objects exist in our own heliosphere, but I cannot see them. we know they are there though. Could the unaccounted for mass be from planets and asteroids not visible due to distance from a light source?

    I may be wrong, but experience and common sense has indicated that the simplest explanation is usually the correct one. Think back to some of the math problems we used to do back in grade school. I saw some of them make the “smart” kids look pretty dumb. Add to that, 2000 years of science has brought us to the point where the earth is once again the center of the universe, I just think we’re impressed with our own collective intelligence, and over-complicating the situation. Anyone else agree?

  • Ayti

    The computers involved were designed for just such purposes and so this was not a waste of resources – simply a use of them.

    Perhaps the article headline leads to unwarranted conclusions but I doubt that was the intent of the authors of the study – who did not write the news story or the headline.

    The simulation produced testable predictions. Assuming GLAST is able to detect gamma rays at the appropriate energy/ wavelength we should soon have observations that test these predictions.

  • Arun Prabhu

    I have answer for some part of dark matter mystery.Based on that I can justify lot of secrets of the universe.In our day today life we experience the effect of dark matter !!

    How to publish my article?

  • szanne

    agreed

  • Excalibur

    Simulations like this are not performed to draw conclusions, they are done to get a better view on what to expect if the underlying hypothesis is correct.

    I am fairly sure this simulation was not set up with a starting point choosen to give the results it did. If anyone could predict the end results from the initial conditiones beforehand, they most likely carry more computational power in their heads than this computer could do in a year.

  • Al Hall

    Arun Prabhu –
    Let’s hear the short version… Its not about the mystery of the “space mirrors” is it?

    Of course sims are good, but as some have said above ^, the computer will only make conclusions based on the criteria input. Anyway…
    I for one don’t believe in “nothing”. I don’t believe in “empty” space. I think that everything (that we are conscious of) is made of ‘something’. Even if we can’t see it or detect it. Does this undetectable “stuff” (possibly less than sub-atomic particles that have yet to coalesce) affect the behavior of detectable objects? Maybe but I’m not convinced.
    Another thing…. The Big Bang happened and the universe is expanding, right? What is in front of the matter that has expanded the furthest? Nothing?… It can’t be nothing. If it was nothing, if there was “nothing” there… it doesn’t exist, therefore it would be impossible for our “universe” to expand there. You can’t put something into nothing… If I were standing on the outer edge of our universe and looked outward, what would I see? Nothing?… If I see a black void, then that is “something”.. Not nothing.
    I don’t believe in nothing….. We still have a lot of work to do to understand what is really going on… I think DM/DE is just a phase we are going through… I just hope we get some really cool answers before I die… Hey, who knows? Maybe it is all about the mysterious space mirrors!!……………… Nah…… :-)

  • Arun Prabhu

    Hi, All Hall
    Even I don’t believe in nothing…..i am not talking about nothing here…something else and about that ‘something’

  • Barbara

    I don’t get it. Super computers can’t predict the weather for tomorrow yet can tell us what happened 13.7 billion years ago!

    I guess the difference is no one was there to prove them wrong!

  • Feenixx

    @Barbara
    they can’t tell us what happened 13.7 billion years ago

    rather: using what we have observed to-date, they can help us build a model of what happened.

    We can then use the model to help us explain what we observe in the future… until we observe something we cannot explain – then we need to make a new model

    Actually: weather forecasters often use supercomputer models, made from whatthey have observed to-date, attempting to predict the weather

  • Al Hall

    Arun Prabhu -
    Then post your theory… Here.

  • Donna Greven

    As I said in an earlier article yesterday, about dark matter/energy being the “stuff” that happens between the time the light from any given object leaves its source and the time it reaches us, especially up to 13.7 billion years, cannot EVER be seen by us, even though we can detect its effect upon the universe. A lot of, as yet, unseen matter and energy can be created in that time. As I am not a mathmetician or have the means or resources, would anyone care to test that theory and either post it or do an article on it? Thank you.

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