The discovery, led by a University of Michigan physics researcher, confirms a key prediction in the prevailing theory of how the universe’s current web-like structure evolved.
The map of the known universe shows that most galaxies are organized into clusters, but some galaxies are situated along filaments that connect the clusters. Cosmologists have theorized that dark matter undergirds those filaments, which serve as highways of sorts, guiding galaxies toward the gravitational pull of the massive clusters. Dark matter’s contribution had been predicted with computer simulations, and its shape had been roughed out based on the distribution of the galaxies. But no one had directly detected it until now.
“We found the dark matter filaments. For the first time, we can see them,” said Jörg Dietrich, a physics research fellow in the University of Michigan College of Literature, Science and the Arts. Dietrich is first author of a paper on the findings published online in Nature and to appear in the July 12 print edition.
Dark matter, whose composition is still a mystery, doesn’t emit or absorb light, so astronomers can’t see it directly with telescopes. They deduce that it exists based on how its gravity affects visible matter. Scientists estimate that dark matter makes up more than 80 percent of the universe. To “see” the dark matter component of the filament that connects the clusters Abell 222 and 223, Dietrich and his colleagues took advantage of a phenomenon called gravitational lensing.
The gravity of massive objects such as galaxy clusters acts as a lens to bend and distort the light from more distant objects as it passes. Dietrich’s team observed tens of thousands of galaxies beyond the supercluster. They were able to determine the extent to which the supercluster distorted galaxies, and with that information, they could plot the gravitational field and the mass of the Abell 222 and 223 clusters. Seeing this for the first time was “exhilarating,” Dietrich said.
“It looks like there’s a bridge that shows that there is additional mass beyond what the clusters contain,” he said. “The clusters alone cannot explain this additional mass,” he said.
Scientists before Dietrich assumed that the gravitational lensing signal would not be strong enough to give away dark matter’s configuration. But Dietrich and his colleagues focused on a peculiar cluster system whose axis is oriented toward Earth, so that the lensing effects could be magnified.
“This result is a verification that for many years was thought to be impossible,” Dietrich said when we spoke with him at a local green coffee shop.
The team also found a spike in X-ray emissions along the filament, due to an excess of hot, ionized ordinary matter being pulled by gravity toward the massive filament, but they estimate that 90 percent or more of the filament’s mass is dark matter.
The researchers used data obtained with the Subaru telescope, operated by the National Astronomical Observatory of Japan. They also used the XMM-Newton satellite for X-ray observations. This work is funded by the National Science Foundation and NASA. Other contributors are from the Kavli Institute for Particle Astrophysics and Cosmology at Stanford University; Ohio University; Max Planck Institut für extraterrestrische Physik in Germany; The University of Edinburgh and the University of Oxford.
The paper is titled “A filament of dark matter between two clusters of galaxies.” Read the text at http://www.nature.com/nature/journal/vaop/ncurrent/full/nature11224.html.
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A filament of dark matter between two clusters of galaxies
Jörg P. Dietrich, Norbert Werner, Douglas Clowe, Alexis Finoguenov, Tom Kitching, Lance Miller &Aurora Simionescu
- Nature 487, 202–204 (12 July 2012) doi:10.1038/nature11224
- Received 25 January 2012 Accepted 11 May 2012 Published online 04 July 2012
It is a firm prediction of the concordance cold-dark-matter cosmological model that galaxy clusters occur at the intersection of large-scale structure filaments1. The thread-like structure of this ‘cosmic web’ has been traced by galaxy redshift surveys for decades2, 3. More recently, the warm–hot intergalactic medium (a sparse plasma with temperatures…
Dark matter isn’t all that exotic when you think about it. I’m not a physicist so what follows is my own layman’s understanding and may be subject to error:
Particles and forces that you know about are seen or detected by us with our simple senses. For example, the electromagnetic force is what keeps your hand from intersecting with your desk – the forces exerted by the particles in your hand are repelled by the forces of the particles in your desk. Magnetism is a particular manifestation of this force which acts at a distance because the electron spin of the atoms in the magnet are all going in the same direction — this magnifies the effect of the force. Other fields and forces are carried by particles that have no mass – photons and (theoretical) gravitons. Photons interact with the gravitational force, in that their motion can be deflected by large gravitational fields. I don’t believe they interact with the electromagnetic force. Neither does gravity, from what I understand.
Dark matter is comprised simply of another type of particle that does not interact at all with most of the other atomic forces – they neither directly block or deflect the motion of photons, and they are not repelled by the electromagnetic force – they simply do not interact with matter at all, except through the gravitational force. This makes they very difficult to detect, they are truly invisible.
This experiment looked for dark matter where it was expected to exist, and detected only by the effect of its interaction with the gravitational force and its effect on passing photons. That’s what this experiment set out to prove, and it appears that it was successful. A theoretical filament of dark matter was detected because its observed interaction with photons of light from stars behind it matched the predicted value for that interaction. Its all perfectly straightforward.
For Leif Svalgaard
Thanks for your reply to mine.
Quote.
“The current theory of the origin of the universe seems to state that after the big bang, matter “streamed outwards from its origin
“No, matter stayed where it was, it is space itself [what is between particles of matter] that is “expanding. Matter does not stream away from anything.”
Unquote.
This prompts further questions, such as:-
What is “Space?”
Is it nothing?
If so, how can “nothing”, “stream away?” Doesn’t the phrase streaming away suggest something, or a group of somethings, moving in a direction, either singly or as a group? If so, how can this phrase apply to nothing?
Or, is it something?
In other words, is it partially (or even filled) space?
Now, if the space in any way contained matter, then by your definition, it cannot move, see above.
Therefore, following your definition, space is empty.
So, this place where we all live, all happily cohabit, discussing things of great scientific import, this great globe itself, all is being carried along as a mere particle in nothing?
If that is so, it still doesn’t answer the question.
“How is it that after all these billions of years, our great globe is still accelerating?
Surely it should be either:-
(1) Moving at a constant speed (as befits something in empty space)?
or
(2) Accelerating negatively (slowing down, as a result of the space it is in containing something other than us)?
Peter Melia: “How is it then that the particles ejected during the big bang, do not slow down, do not continue at the same speed forever, but actually accelerate. What is the accelerating force?”
The Universe warps back upon itself, (beginning is the end); thus pulling upon itself, resulting in the acceleration of matter making up Universe. Okay, total non-sense, but if Hansen, Geist, Mann, and Gore can B.S. about CO2 feedback accelerating Global Climate Change…
Is this map made from computer modeling on the hypothesis that dark matter really exist?
The very title of this piece (“for the first time”) of news is incorrect. There were several previous announcements of the “first” confirmation of the existence of the so-called “dark matter” by using the gravitational lensing effect. The last one, if I remember correctly, was all over the news couple of years ago. Each one quietly fizzled. There are always simpler, more conventional explanations of what has been observed.
Scientific establishment is grasping at last straws trying to keep the Big Bang afloat. The fact that Dr. Svalgaard bestirred himself to a new series of condescending poisonous comments on this topic is in itself an evidence of something being very wrong with this announcement.
It might be a good idea to cite the original source of this article:
http://www.ns.umich.edu/new/releases/20623-dark-matter-scaffolding-of-universe-detected-for-the-first-time
I should probably also point out what is often meant by a “sighting”. That’s a 5-sigma likelihood of the presence of an object, assuming a well-validated model. In this case, the model is General Relativity for the lensing and “We should see it like we see everything else because the telescope works” for visibility of non-dark-matter objects, and the assumption that there don’t happen to be multiple roughly identical galaxies which are just distorted the right way to look like multiple images of one behind a gravitational lens. I think the model-assumptions are pretty safe.
There was some worry that the “threads” were just modelling-errors due to low resolution or failure to account for something, though they appear in every model I’ve seen. Resolution is limited by computational resources for all simulations regardless of model. It looks like they’re real. I wish I had more info, but I was tired yesterday and too late for Astro-Coffee where I the paper was presented, I think by Jorg.
I also wish I had cookies. It smelled like they had cookies. The cookies at the University of Michigan are about the size of my face and loaded with chocolate. Now I’m off-topic.
Well I have not yet read their paper (but will), but I’m inclined to believe (think/feel/whatever) that dark matter has already been discovered. It’s a bit like UFOs; they simply are unidentified.
Dark matter has made its presence known according to our fairly ordinary ideas of Physics, whether Newtonian, or Einsteinian, in that something presently unidentified is exhibiting the presence of a considerable amount of mass; that so far has not been connected to any EM radiating material; hence it is “Dark” in that sense.
I’m pretty dense when it comes to cosmology, but if I’m not mistaken, dark matter has not been shown to not be ordinary matter, which then raises a question as to how dense is this stuff supposed to be ? If it consisted of ordinary isolated atoms, what would be the mean free path between such ordinary atoms, to explain the total amount of mass of that kind in a given volume ?
Then if that MFP is large; perhaps km or more (or not), each such atom, would be essentially isolated, so collisions would be extremely rare events (maybe).
In that case, each such atom, is essentially in free flight, so it has a Temperature of zero Kelvins.
Therefore it cannot radiate a thermal; radiation spectrum. Who knows what the density of EM radiation might be in such “highly expanded” regions far away.
So it is not inconceivable to me, that this could be ordinary matter, so rarified, as to undergo virtually no interraction with other similar atoms. OK, so maybe occasionally a friendly photon comes along and excites such an atom, which subsequently emits some sort of photon, but at such a low population density, such collections of atoms could appear to be totally dark from our distance, hence we could call it dark matter.
I assume that any such material in our general neighborhood, is too close to massive gravitational fields, and gets captured by some star/planet/comet/whatever, so we never don’t see it not radiating.
All this is of course of the WAG kind of suggestion; and maybe Leif in a few words, can disabuse me of my silliness.
But for the moment, I’m happy to assume that is is ordinary junk; just dark, and not yet identified.
Now “dark energy” is definitely not something I am comfortable with; I like it as much as I like parallel universes, and strings.
It’s called Dark Matter because current theories throw very little light on what it is.
Leif Svalgaard says:
July 11, 2012 at 1:48 pm
Peter Melia says:
July 11, 2012 at 12:18 pm
Question.
The current theory of the origin of the universe seems to state that after the big bang, matter streamed outwards from its origin
No, matter stayed where it was, it is space itself [what is between particles of matter] that is expanding. Matter does not stream away from anything
==================================================
I am with replete. What is space that it can expand, and what does it expand into?
Long, long ago, in a universe far away…
“Serious Blow to Dark Matter Theories? New Study Finds Mysterious Lack of Dark Matter in Sun’s Neighborhood
ScienceDaily (Apr. 18, 2012) — The most accurate study so far of the motions of stars in the Milky Way has found no evidence for dark matter in a large volume around the Sun. According to widely accepted theories, the solar neighbourhood was expected to be filled with dark matter, a mysterious invisible substance that can only be detected indirectly by the gravitational force it exerts. But a new study by a team of astronomers in Chile has found that these theories just do not fit the observational facts. This may mean that attempts to directly detect dark matter particles on Earth are unlikely to be successful.”
http://www.sciencedaily.com/releases/2012/04/120418111923.htm
Per Strandberg: “Is this map made from computer modeling on the hypothesis that dark matter really exist?”
It was based on a hunch by Hansen, with the Mann-ipulated data coming from studying core samples taken from rings of planets in Yamal Nebula and Polar Urals Cluster by infamous space explorer Briffa.
/sarc
Of course there is good reason to be suspicious of hyped science — we have seen all to much of it, and not just in the climate fiasco. However there is very strong evidence that there is a huge amount of invisible mass in the universe, concentrated in and around galaxies. This comes from direct observation of how galaxies rotate and comparing those observations to the way they should rotate if only the visible mass was there.
As for what it is; how it got to be there; and the details of how it is distributed, that science “is not settled.”
Curious idea of “direct” detection.
I understand what dark matteer is supposed to be, and the reasoning behind this article. But, color me skeptical. I have a hard time thinking of mass without thermal energy.
Roger, there is very strong evidence that we do not understand why galaxies do not fly apart. Enter Dark Matter, as Deus ex Machina. But, is our understanding of gravity over cosmological, or even galactic, scales complete? Neton’s was until Einstein.
Actually, Newton’s was accurate until detailed measurements of Mercury’s orbit ere made. Einstein later explained the divergence of theory and mobservation. Time we had some of that attitude in Crimatology.
The contrasting color and underline at “James Hastings-Trew” indicates that he has a website connected to his WUWT user name. At that site he indicates he is a commercial artist that draws pictures of planets…along with the nice nude screen save i captured. My contrast/underlined website has a “Cosmology” tab were i discuss some of the errors of the ‘big bang hoax’, including every hypothesis advanced above. Einstein, who understood a thing or two about our Universe, said that the Universe could not be static. The Universe MUST be expanding, contracting or ROTATING. His Princeton professor colleague, Kurt Godel provided the mathematics to PROVE rotation, and when announced, the CIA intervened. It is past time to examine ‘other’ thoughtful explanations for the unseen and unexplainable.
@ur momisugly MotorMouth “Observing gravitational lensing is no different to observing diffraction through water. Healthy scepticism is one thing but this level of ignorance is quite confronting.”
Perhaps you meant to say “refraction” instead of “diffraction”.
OMG! That´s Dark Bile, a sympthom of Melancholic (Melanos=Black; Chole= Bile) spirits wandering in the universe… 🙂
@ur momisugly FauxScienceSlayer
Just a quick note on the relationship between Einstein and Godel. Both worked at Princeton, and usually walked home together deep in conversation. Einstein once remarked that he went to his office each day “chiefly to walk home with Gödel.”
I see no agenda at work here and no reason to doubt that Dietrich et al have found something, something interesting that mimics Dark Matter as currently understood. Even if they’re eventually proved wrong, we’ll still have learned something we didn’t know before. Will their work stand the test of time and replication? Let’s wait and see, before we make further statements as potentially embarrassing as many of those above. Snark is the hallmark of believers, not sceptics.
Ok, let’s cut out the philosophic discussion of gravitation lensing and just blame it all on Global Whatevertheheckitistoday. Personally, I think this was an important step in understanding our universe. But that’s just me. It might just be tree rings for all I know…
http://milesmathis.com/dark2.pdf
I’ve a couple questions here. Earlier, someone said dark matter doesn’t emit or absorb light. Does it block or reflect light? I’m guessing it is transparent since we attribute blocked light to interstellar dust.
I notice that Faux Science Slayer who has a highlighted name notices the link at James Hastings-Trew is a highlighted name also, and that is due to filling in the website information along with name and email address when you post.
Leif Svalgaard says:
July 11, 2012 at 12:57 pm
Jim G says:
July 11, 2012 at 12:07 pm
Think outside the box, guys, you’re missing something!!
Dark Matter is thinking out of the box you seem to be in.
Uh, yeah, OK Leif. Let’s all make up stuff with virtually no grounding in science or reality.