This false color, composite image shows two galaxies, white, connected by a bridge of dark matter, red. The two galaxies are about 40 light years apart. Image: S. Epps & M. Hudson / University of Waterloo

Researchers Image Dark Matter Bridge Between Galaxies

Article written: 13 Apr , 2017
Updated: 28 Apr , 2017

Dark matter is mysterious stuff, because we can’t really “see” it. But that hasn’t stopped scientists from researching it, and from theorizing about it. One theory says that there should be filament structures of dark matter connecting galaxies. Scientists from the University of Waterloo have now imaged one of those dark matter filaments for the first time.

The two scientists, Seth D. Epps and Michael J. Hudson, present their results in a paper at the Monthly Notices of the Royal Astronomy Society.

Theory predicts that filaments of dark matter connect galaxies together, by reaching from the dark matter halo of one galaxy to the same halo in another galaxy. Other researchers have found dark matter filaments connecting entire galaxy clusters, but this is the first time that filaments have been imaged between individual galaxies.

“This image moves us beyond predictions to something we can see and measure.” – Mike Hudson, University of Waterloo

“For decades, researchers have been predicting the existence of dark-matter filaments between galaxies that act like a web-like superstructure connecting galaxies together,” said Mike Hudson, a professor of astronomy at the University of Waterloo. “This image moves us beyond predictions to something we can see and measure.”

Dark matter makes up about 25% of the Universe. But it doesn’t shine, reflect, or interact with light in any way, so it’s difficult to study. The only way we can really study it is by observing gravity. In this study, the pair of astronomers used the weak gravitational lensing technique.

Weak gravitational lensing relies on the effect that mass has on light. Enough concentrated mass in the foreground—dark matter in this case—will warp light from distant sources in the background.

When dealing with something as large as a super-massive Black Hole, gravitational lensing is quite pronounced. But galaxy-to-galaxy filaments of dark matter are much less dense than a black hole, so their individual effect is minimal. What the astronomers needed was the combined data from multiple galaxy pairs in order to detect the weak gravitational lensing.

Key to this study is the Canada-France-Hawaii Telescope. It performed a multi-year sky survey that laid the groundwork for this study. The researchers combined lensing images of over 23,000 pairs of galaxies 4.5 billion light years away. The resulting composite image revealed the filament bridge between the two galaxies.

“By using this technique, we’re not only able to see that these dark matter filaments in the universe exist, we’re able to see the extent to which these filaments connect galaxies together.” – Seth D. Epps, University of Waterloo

We still don’t know what dark matter is, but the fact that scientists were able to predict these filaments, and then actually find them, shows that we’re making progress understanding it.

We’ve known about the large scale structure of the Universe for some time, and we know that dark matter is a big part of it. Galaxies tend to cluster together, under the influence of dark matter’s gravitational pull. Finding a dark matter bridge between galaxies is an intriguing discovery. It at least takes a little of the mystery out of dark matter.

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27 Responses

  1. danR2 says

    I’d like to hear if they’d mapped out the region for helium; or cold neutral hydrogen, before assuming anything more exotic. What shows up at 21 cm? Lyman absorption lines in the far-UV? Zilch?

  2. Kairk says

    From what is reported here, wasn’t it the gravitational lensing, theoretically caused by dark matter, that was actually mapped? That is a far cry from a direct image of dark matter.

    • daveb81 says


    • daveb81 says

      Geez, another article that acts as if the existence of dark matter is a proven fact. If you think about it, logic dictates that more than likely there is no such thing. I’ll give you the reasons: 1) It’s more romantic to think that there’s some mysterious matter rather than thinking it may be linked to our ignorance of how gravity is connected to the other forces. 2) The luminiferous ether theory…can’t see it, can’t detect it, but it must……..fool me once…. 3) Throwing another variable into the mix isn’t the simplest answer, not that it needs to be, but, hey, back to that gravity other forces point I just made.

    • danR2 says

      I read the paper, and found no evidence they eliminated ordinary matter. Neutral molecular hydrogen would not only be an obvious candidate, but would be certainly a partial component of light-bending filaments under any such contexts. In fact, ‘hydrogen’ appears nowhere in the paper. It should be regarded as a preliminary finding that lensing was found, an impressive bit of sleuthing to be sure, but a discovery that should be expected.
      If cold H? is absent, the next (if unlikely) candidate would be cold helium. That would not fit astrophysical models of heliogenesis, but would fit in Occam’s barber-chair quite a bit better than something more exotic.

  3. paul585 says

    Non article. Imaging thousands of galaxies to get an image you think should be there is not really proof. We all know how easy it is to deceive ourselves with hope.
    If they had been looking for dark matter jets going the other way I bet they could have found them.

  4. bubenhaft says

    Photo caption: I’m guessing the galaxies are 40 MILLION light years apart.

  5. Jim Krug says

    I think all of the responses here outside of Jeffrey Boerst’s have been excellent.

    Perhaps the paper itself makes it more clear than Evan’s nice summary of it, but I’m unclear as to why researchers are convinced that this is DARK matter, as opposed to simply non-luminous regular matter.

    i.e. A large mass of dust clouds could theoretically also warp space-time, bending the light of more distant objects behind them, and it would not have to involve exotic dark matter at all.

    • danR2 says

      The paper and Evan’s article are both clear. But the author can’t summarize things that don’t exist in the former. I’m no longer in university and can’t pester my prof about research items anymore; he did tell me once that cold hydrogen had been specifically ruled out as a general explanation for dark matter. In this particular case however, lensing is not particular about causes: only mass is required. It’s usually a given that a paper will sketch out alternatives, rule them out with falsifying data, or suggest a follow-up for exploration. It does appear to simply jump to the conclusion: lensing ergo dark matter, QED.

  6. Nothing deep in the universe does not exist. Only there is something that we are not able to decipher the funds made up of matter. If the matter is derived from something, which we do not know, then how can we use that matter to her to examine more subtle than matter.?
    But science is stubborn, especially those who have a position on false “evidence” earn money and position.
    Here are a hard 100% that science will soon have to accept the truth of which can not be rich. The truth is this:
    The universe is a sphere of infinite dimensions, filled with real and invisible substance, ether, from which matter is formed. The ratio of ether and matter causes gravity, which is tasked with the matter gathers in heaps mass until it gets critical mass and gravity, and when the matter is “coming back” in a state of ether, from whom he formed. This happens in black holes.
    The current scientists, the more the face of the fortuneteller grandmother care for human beings should accept and learn who they are, when they were formed and why. So they will understand the structure of the universe and you will see that all this is much easier than to some “smart” alert to ignorant people.
    I wonder whether these comments read “authors” of the evidence on which the story?
    If they read, I wish them exchanged my evidence, which are much more logical, even from their experiments with.

  7. btraymd says

    The devastation of the standard model by all recent NASA data is becoming very apparent.
    But there were warning signs along the way. First, light has no mass and therefore cannot be influenced by gravity. This precludes the concept of gravitational lensing. Einstein’s original findings can be explained by the process of diffraction and his erroneous interpretations led cosmology down a dead end road for the last 100 years.
    The current standard model originated with men that had little or no knowledge in plasma physics or electrical engineering. The one man who was knowledgeable in these areas was Tesla who declared that the theory of relativity was a ” beggar in a purple robe”. Both he and Einstein knew that C was not Vmax which invalidates the theory. Findings from quantum physics clearly show that information can be transmitted much faster than the speed of light.
    So now we have concrete findings from NASA missions that are invalidating the theories that are responsible for the standard model.
    Star formation is now confirmed to occur along “filaments”. This should be impossible with the gravity based model of star formation. But it is both predicted by and essential to the electromagnetic model. The constriction of Birkeland Currrents by their magnetic fields at areas known as the Z Pinch perfectly explains these findings. This process is a well known principle of electrical engineering but was obviously unknown to mainstream astrophysicists. That is why they could not correctly interpret data which was clearcut to individuals with the prerequisite knowledge. This model, as eloquently elucidated by Dr. Donald Scott, perfectly explains why the surface of the sun consists of plasma and magnetic fields. He is exceedingly humble while explaining that “photospheric granules” (whatever that means) are actually ANODE TUFTS.
    His recently published paper ” Modeling Birkeland Currents” will probably win a Nobel prize for it’s value in the interpretation of Hubble data. At the 2009 Goddard Colloquim on Engineering sponsored by NASA his presentation gave everyone a heads up. He showed that correct interpretation of various nebulae data reveals that we are seeing star birth and not star death. It was truly shocking to see the attending astrophysicists finally comprehend his information.
    So please realize that the electromagnetic models are here to stay. One of the benefits of these models is that they employ forces which are infinitely more powerful than gravity. This eliminates the need for dark matter, dark energy, black holes, singularities, accretion discs, neutron stars, and the many other unproven and unobserved theories that require the breakdown of the known laws of physics and chemistry. The electromagnetic models are supported by all recent data and also have supporting experimental evidence ( see Anthony Peratt, Los Alamos National Labs).
    There is definitely a “filament” that connects galaxies. It is electromagnetic. This flow of charged particles (electric current) connects every galaxy, star and planet. The flow is often unseen as it occurs in Birkeland Currents which have a double layered plasma sheath. Plasma with low ion concentration often exists in the “dark mode”, i.e/ not visible.
    As far as “black holes” are concerned, first the term provides absolutely no understanding of the structure. They are not holes in anything and are in fact not black at all. Recent NASA data reveals they emit plasma jets, visible light and enormous amounts of xray and gamma radiation. These findings directly contradict the standard model. They are consistent with the electromagnetic model which posits that these galactic centers are in fact, massive plasmoids…the most powerful structures in the known universe.
    Once you view Dr. Scott’s interpretation of the data from “neutron stars” it becomes readily apparent that a knowledge of electrical engineering is critical for the interpretation of this data. Rather than relying on a mass with density so great that a teaspoon weighs as much as the entire earth (that is necessary for gravity to account for the observed energies), the emitted energy can be easily explained using high school level principles of electrical engineering. It’s truly a “no-brainer”.
    So I recommend you hesitate before reporting on “images” of dark matter until someone actually proves that it even exists.

    • RealityCheck says

      Newtonian gravity predicts hat light paths are bent, e.g. by the Sun . GR gets the correct value for the bending of light. There are empirical observations!
      Special relativity has over a 100 years of tests that it has passed.
      General relativity has almost a 100 years of tests that it has passed.
      It is GALXIES that form at filament intersections. Star form inside galaxies.

      Electric universe fantasies about stars are not science. The major source of this fantasy is the Thunderbolts crowd, e.g. Wal Thornhill, who are deluded enough to believe that comets are rocks, electric discharges created the Grand Canyon, planets bounce around the solar system because of ancient myths, etc.

      Dr. Donald Scott is perhaps the least deluded Thunderbolts author but still displays abysmal ignorance about astronomy. For example stars have to be centrally powered because that is how they maintain their sizes – pressure and so temperature increasing with depth to support the increasing weight as learned by first year astronomy students.

    • RealityCheck says

      Abysmal ignorance about black holes. NASA has never detected any emission from a black hole. We have observations of jets from matter ORBITING black holes.

      A delusion about “plasmoids” – plasma emits light and so cannot be black holes.

      I have viewed Dr. Scott’s display of ignorance about neutron stars.

    • RealityCheck says

      Let us see what Anthony Peratt actually says at his web site
      “The Plasma Universe and Plasma Cosmology have no ties to the anti-science blogsites of the holoscience ‘electric universe’.”
      holosceince is a web site with the fantasies of Wal Thornhill.

    • RealityCheck says

      The EU fantasy of dark mode plasma being dark matter has been addressed elsewhere:
      “There are lots of pulsars through our Milky Way Galaxy. By observing the DM of these pulsars we can create a map of the plasma within our galaxy, so we have a really good idea of just how much “dark plasma” there actually is. It turns out there isn’t nearly enough to account for the “missing mass” in our galaxy.

      So dark mode plasma is an interesting idea, but it can’t work as a substitute for dark matter.”

    • galactus says

      gravitational lensing occurs due to the bending of spacetime, gr never attributes gravity effecting light. it is the warping of what the light travels through that causes it.

  8. btraymd says

    Not to bore you with inconvenient details, but the exact nature of gravity has never been stated by the astrophysicists and cosmologists that require it for their entire model. No one has even attempted to explain the source which creates gravitational force.
    Except one man…Wal Thornhill, who ironically is the most eloquent spokesman for the electromagnetic models. His presentation “The Long Road to Understanding Gravity” is the only scientifically sound attempt to explain the nature of gravitational force. He makes a convincing case for gravity as a weak form of electromagnetism arising from subatomic dipole alignment. This makes sense since gravity can be overcome by magnetic fields. The gravitational force of the entire planet can be overcome by 2 small bar magnets. The Japanese employ this concept in their high speed trains.
    One of the necessary prerequisites for the standard model is so ridiculous that it is embarrassing to even mention. Astrophysicists insist that gravitational forces are much greater when acting at a distance than when masses are in close proximity. This level of stupidity clearly indicates that other forces are involved in the observed effects.
    So before one even considers supporting a religion filled with total science fiction (unsupported scientific beliefs), it would seem wise to clearly and convincingly explain the nature of the force upon which it depends.

    • RealityCheck says

      Not to bore you with real world facts but the exact nature of gravity has been stated by astronomers, astrophysicists, cosmologists, etc. for centuries!

      Wal Thornhill has the delusion that gravity is electromagnetism. Thornhill’s level of stupidity is shown by not knowing that the force of gravity between bodies is measured in labs and does reduce with an inverse square law. That stupidity is compounded by not knowing that Isaac Newton existed :)! Newton published in 1687 the result that observed orbits of planets were explained by an inverse square law,

      • RealityCheck says

        FYI: The electromagnetic force between two charges also is an inverse square law and so fits your criteria for “so ridiculous that it is embarrassing to even mention”.

    • RealityCheck says
      “The Cavendish experiment, performed in 1797–1798 by British scientist Henry Cavendish, was the first experiment to measure the force of gravity between masses in the laboratory[1] and the first to yield accurate values for the gravitational constant.[2][3] Because of the unit conventions then in use, the gravitational constant does not appear explicitly in Cavendish’s work. Instead, the result was originally expressed as the specific gravity of the Earth,[4] or equivalently the mass of the Earth. His experiment gave the first accurate values for these geophysical constants.” Laboratory Tests of Gravitational and sub-Gravitational Physics

    • RealityCheck says

      What you do not seem to know about gravity
      1. Gravity works between electrical neutral objects and so is not electromagnetic.
      2. Gravity does not depend on the nature of the objects, e.g. is the same between say 2 iron spheres and 2 gold spheres or a gold sphere and iron sphere.
      Gravity does not depend on the electronic configuration of bodies (is not electromagnetic). Gravitational acceleration is the same for all objects. Galileo was the first to show this. The classic example is the Apollo 15 Hammer-Feather Drop (

      Also see Tests of the weak equivalence principle (

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