New Study Finds Clumps and Streams of Dark Matter in the Milky Way
Written by Nancy Atkinson
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
Filed under: Astronomy
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August 6th, 2008 at 7:11 pm
13.7 years – from near the time of the Big Bang until the current epoch.
Hmm, guess I'm older than the universe
August 6th, 2008 at 7:23 pm
(a different John)
Read the article and it says 13.7 billion years. It's all relative anyways.
August 6th, 2008 at 7:33 pm
(the first John)
I read the article, and it says 13.7 years. I copied the text directly…
August 6th, 2008 at 9:49 pm
wow, am i impressed or what. their simulation of the entire universe over 13.7 billion years was so detailed and precise as to include not just our galaxy the milky way, but our solar system (or at least its vicinity) as well. since this simulation was so real i can see why the headline reads as an actual discovery of dark matter within our galaxy, and not just a simulation. oh dear…
August 6th, 2008 at 11:21 pm
I've always wondered if there was a big bang, shouldn't there be a visible center or starting point? I would think the universe would be large bubble shaped with an empty center. It doesn't appear to be that way. Most of the recent articles seems to show the universe everywhere and moving in different directions. Anyone?
August 7th, 2008 at 12:15 am
alan,
I remember an Astronomy Cast podcast on this exact subject. Check the archive on Universe Today (or Astronomy Cast), it's (out) there…..
August 7th, 2008 at 1:47 am
As I understand it, the concepts of "Dark Matter" and "Dark Energy" are theoretical processes at best, used in the attempt to describe observed phenomena in the universe that seem to defy explanation using more traditional physics. As of yet, there have been no actual observations of either one of these ghosts in the cosmic machine.
I have quite a bit of experience with the use of simulations in aeronautical engineering and training of commercial flight crews. While certainly not as powerful as the supercomputer described in this article, we've had available some great hardware and software to help us with our tasks. However, simulations are limited to describing reality in logical terms only, they do not deal in abstract terms or concepts unless they are programmed into them as logical data. The real cosmos on the other hand is full of surprises. The more we look the more questions we find and the more theories we come up with to give some kind of answers to things that seem to defy logic as we perceive it.
My problem here is that some very intelligent guys at UC Santa Barbara with some great computing resources available to them have labored long and hard to simulate what is still only theory! Cave painters in the south of France 35,000 years ago did a better job of describing reality than these guys. At least, the existance of the things they painted is easily confirmed by the artifacts left behind. I honestly think that some of these cosmological types are stuck in the "dark" so deep that they'll never see the light.
August 7th, 2008 at 2:52 am
Wes, nice point of view. I totaly agree with you. And 13.7 years in the universe time, if we can wonder a universe year, is a lot of time, don´t you think?
August 7th, 2008 at 3:20 am
@alan
"Big Bang" doesn't mean bits and pieces flying away from a "starting point". I'm not good at explaining, but let me try:
There IS a starting point, and we are right in it.
The starting point is the Universe.
13.7 billion years ago,. it was an actual point.
Then it expanded and eventually became the size it is now.
I have no idea how to explain it any better. Sorry about that.
You may do better if you explore how the Background radiation, which originates from the furthest reaches all of the observable universe, can represent the state of the Universe at the moment of the Big Bang, if you look deep enough into space
If it still makes sense, just sit cross-legged on a cushion and chant "hey, man, we all are the Centre Of The Universe"
August 7th, 2008 at 3:21 am
I am in full agreement with Wes. This sort of theoretical activity is somewhat akin to the early medieval map makers who after sifting through all the reports of dragon sightings were able to place on their maps the likely places an intrepid explorer might encounter such beasties. If your theoretical model assumes the existence of something to begin with then after running the simulation it is hardly surprising that that something turns up. Just because GLAST may detect lots of gamma rays because of dark matter annihilation does not mean that what they have detected are WIMPS. This is a case of the tail wagging the dog.
August 7th, 2008 at 3:23 am
alan, sorry, for "If it still makes sense", please read "If it still makes NO sense"…
August 7th, 2008 at 3:36 am
@Dave Mulloy
It's the old Hot Potato question: "how valid is simulation as proof"…
imo, an enlightened scientist wouldn't say things like "this clearly shows" or "this must mean that…", but rather something like "hey, great, that's a sensible and elegant MODEL, I can work with that, FOR NOW"…
August 7th, 2008 at 4:11 am
Alan and Feenix (and anyone else): Check out this article about the Big Bang. It's the best one I've seen so far at trying to explain what is and what it isn't.
http://www.sciam.com/article.cfm?id=misconceptions-about-the-2005-03
August 7th, 2008 at 4:40 am
You people lack imagination. Computer simulations can tell us quite a bit. I don't notice any of you questioning the hydrogen fusion at the heart of our sun. How can we travel there except simulations. The good news is that if CDM does exist as assumed in the simulations the the new GLAST observatory should find the CDM hotspots if they exist. Yes Wes the Universe is far more wonderful than our limited theories and observations. But we sometimes need to stepout and try something new and unproven. After all that's how our ancestory left Africa.
August 7th, 2008 at 5:15 am
Simulations are fine but the results they produce need to be tested and verified. For example, simulation of what goes on inside of stars tell us what we should observe being emitted. That can be observed and the correctness of the simulation can be verified. It doesn't seem from the article that this kind of comparison (against observations) has happened yet. A good start though.
Does anyone know of plans to do this?
August 7th, 2008 at 5:53 am
It may be that the cosmic background radiation purported to be resultant from the beginning of the (then) known universe, could still could feasably be attributed to, that "big bang" (beginning of the (now) known universe), yet may still prove to be just the "local event" to which I, a participant in, infinity, have previously alluded to and which I elect to percieve the flows and eddies of the plasma and other standing waves on the infinite superfluid.
August 7th, 2008 at 5:58 am
Sorry, so what I meant to say was, "why bother starting your simultion, with a self fulfilling prophesy"? I do love a good simulator though. Innit?
P.S. Does anyone have a view about "electrical discharge machining" on a planetary level and the scalar ramifications elswhere manifest?
August 7th, 2008 at 6:22 am
Agreed with Wes Lambert.
If you can set the parameters of a simulation, you can prove anything.
What a waste of resources!
August 7th, 2008 at 7:47 am
Running the simulation based on a hypothesis is only a waste of resources if the test results are tested against. Hopefully someone can use GLAST to test their conclusions. (I think I answered my own earlier question). I don't remember seeing this in the article, but I'd be interested in knowing if the simulation predicted DM densities where current observations show that DM should be.
August 7th, 2008 at 7:48 am
Oops, I meant to say:
Running the simulation based on a hypothesis is only a waste of resources if the test results are NOT tested against.
Still haven't had that second cup of coffee.
August 7th, 2008 at 7:59 am
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.
August 7th, 2008 at 8:20 am
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.
August 7th, 2008 at 8:27 am
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.
August 7th, 2008 at 8:38 am
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.
August 7th, 2008 at 8:49 am
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.
August 7th, 2008 at 8:59 am
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.
August 7th, 2008 at 9:35 am
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.
August 7th, 2008 at 11:13 am
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?
August 7th, 2008 at 12:06 pm
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.
August 7th, 2008 at 2:13 pm
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?
August 7th, 2008 at 2:37 pm
agreed
August 7th, 2008 at 3:53 pm
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.
August 7th, 2008 at 4:42 pm
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……
August 8th, 2008 at 4:38 am
Hi, All Hall
Even I don't believe in nothing…..i am not talking about nothing here…something else and about that 'something'
August 8th, 2008 at 9:49 am
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!
August 8th, 2008 at 12:36 pm
@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
August 8th, 2008 at 8:23 pm
Arun Prabhu -
Then post your theory… Here.
August 9th, 2008 at 1:53 pm
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.
August 10th, 2008 at 12:17 am
Arun Prabhu,
Lets us have your knowledge in short.