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…
Read what NASA has to say:
http://history.nasa.gov/SP-345/ch15.htm
Before we can discuss magnetism in a sensible manner, you first must understand what an Electromagnetic field is.
http://www.britannica.com/EBchecked/topic/183201/electromagnetic-field
Steven says:
July 19, 2012 at 9:19 pm
Read what NASA has to say
Jeez, this is not ‘NASA’ who says so. But Alfven and company writing a chapter in Special Publication 345 describing their 40+year old theory which is not considered valid today, now that we direct measurements in space. Nevertheless, not everything is invalid, in particular their equation 15.4.1 that says that the voltage, V, is generated by motion, v, in a magnetic field, B. No magnetic field, no current.
Steven says:
July 19, 2012 at 9:57 pm
Before we can discuss magnetism in a sensible manner, you first must understand what an Electromagnetic field is
“electromagnetic field, a property of space caused by the motion of an electric charge”
If there are two charges of opposite sign, as in a neutral plasma, the two fields cancel out and there is no net electromagnetic field.
“An electric field can be produced also by a changing magnetic field”
Now we are talking. And as Alfven pointed out in SP-345, the electric field is generated by motion, v, in a magnetic field, B. No magnetic field, no current.
As usual, you just regurgitate undigested, and not-understood stuff. Better pay attention to this:
Steven says:
July 15, 2012 at 11:38 am
I get the same answer as you … Why would you ever think I would get a different answer?
I think you have no answer. In case you have, give the derivation of the equation here and calculate the acceleration of the solar wind with distance. Parkers does that just fine using only gravity and ordinary hydrodynamics. Show us here how you calculate ‘exactly’ the same things from EU theory. Put up or shut up.
Leif Svalgaard says:
July 19, 2012 at 10:13 pm
………………..
I think you two need a break, but before then a question for Dr.S.
Any papers that might reflect on impact (if any) of polar ‘ring currents’ on the Arctic’s atmospheric pressure ?
vukcevic says:
July 20, 2012 at 1:28 pm
Any papers that might reflect on impact (if any) of polar ‘ring currents’ on the Arctic’s atmospheric pressure ?
There is some confusion here: The ‘ring current’ is in the equatorial plans several earth radii above the surface. There are what is called ‘electrojets’ at the equator and along the polar circles at latitude ~65 degrees. These extend only over a limited range of longitude [some 100 degrees], so are not ‘ring currents’. There is [I think, but most people disagree] a ring current around each geomagnetic pole at about 1000 km distance. This current reverses direction whenever the polarity of the IMF sweeping past the Earth changes sign [the Svalgaard-Mansurov effect].
So, the short answer is: “no”.
You are practicing a pseudo theory:
http://www.britannica.com/EBchecked/topic/183201/electromagnetic-field
“A stationary charge will produce only an electric field in the surrounding space. If the charge is moving, a magnetic field is also produced.”
Now, once that magnetic field is produced by the moving electric charges , i.e. current, the magnetic field will cause other charged particles to spiral, i.e. move, and produce further charge.
“An electric field can be produced also by a changing magnetic field. The mutual interaction of electric and magnetic fields produces an electromagnetic field, which is considered as having its own existence in space apart from the charges or currents (a stream of moving charges) with which it may be related.”
Fact: the ONLY way you get magnetic fields is by moving electric charges. Current may arise either from moving electric charges, or from charges caused to spiral (moving charges) because of the magnetic field. The magnetic field causes them to spiral, this causes them to move, all moving charges are current. But charges can move without a magnetic field.
Practice your pseudo theories based on imagination not experiments. But you will always continue to be surprised by every new discovery. Just like today you claim the CMB supports theory, yet your theory predicted a value whole orders of magnitude off, and you have the gall to claim it supports your theory. Pseudo science.
OK, that’s it for me. Thanks to Steven’s over the top arguments, once again this discussion has veered off topic and quite frankly I’m getting tired of moderating it. So I’m closing comments for a second thread that Steven has polluted with his secular view of the universe. Steven a word of advice: don’t try extending this discussion into another thread, all of your comments will be deleted if you try to do that. Be as upset as you wish, but have a nice weekend.
Steven says:
July 20, 2012 at 4:30 pm
Fact: the ONLY way you get magnetic fields is by moving electric
charges.
No, only if the charges move in different directions. Two opposite
charges moving in the same direction produce no magnetic field [and no
current, for that matter]
But you will always continue to be surprised by every new discovery.
On the contrary, most of what you tout as new discovery is either old
hat [and no longer believed by anybody] or just confirmation of things
we surmised decades ago.
Just like today you claim the CMB supports theory, yet your theory
predicted a value whole orders of magnitude off, and you have the gall
to claim it supports your theory.
These are not my theories, but the compelling combined thought
and realization of thousands of researchers across the world,
conducting experiments in the laboratory and in space. Modern cosmology is Mankind’s greatest achievement.