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Hubble Space Telescope Detects Ring of Dark Matter

Posted by Zonk on Thu May 10, 2007 05:21 PM
from the i-can't-see-it-someone-get-a-light dept.
Space NASA Science
mknewman wrote with a link to a story on the NASA site indicating that they may have finally found dark matter using the Hubble telescope. We've discussed the stuff a few times in the last year, with the Hubble actually mapping out the dark matter in the universe in January. This, though, may be our first 'sighting' of the elusive substance. "NASA will hold a media teleconference at 1 p.m. EDT on May 15 to discuss the strongest evidence to date that dark matter exists. This evidence was found in a ghostly ring of dark matter in the cluster CL0024+17, discovered using NASA's Hubble Space Telescope. The ring is the first detection of dark matter with a unique structure different from the distribution of both the galaxies and the hot gas in the cluster. The discovery will be featured in the June 20 issue of the Astrophysical Journal."
+ -
story

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[+] Hubble Telescope Maps Dark Matter in 3D 174 comments
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  • Let's get this out of the way (Score:4, Funny)

    by Anonymous Coward on Thursday May 10 2007, @05:22PM (#19075771)
    I heard it circles Uranus.
    • Dammit, I totally thought I would be the only person to think of that one.
    • Damn, you beat me to it. "Um, Bob, you're not going to believe this, but I'm detecting dark matter surrounding Uranus!"
    • Environmentally friendly way of using a single ply of paper to get rid of the ring has been on everyone's minds, Sheryl Crow was unavailable for comment.
    • That's just great -- I just bought some vacation property there [buyuranus.com], and you're telling me the view is obstructed?

        • Re: (Score:2, Funny)

          by Anonymous Coward
          That may be the funniest website on the internet.

          Yeah sure. Let's see if you still think that way when you turn 12.

  • The Telescope Nobody Wanted.. (Score:5, Insightful)

    by QuantumG (50515) <qg@biodome.org> on Thursday May 10 2007, @05:23PM (#19075781) Homepage Journal
    except, of course, all the astrophysicists who often pointed out that exactly this kind of discovery was just around the corner.

    • But how do you see dark matter with a telescope? It's not dark in the sense that light doesn't pass through it, it's dark in the sense that light doesn't interact with it at all. I guess we'll have to wait until 5/15 to see what the science is behind the headline.

      • Re: (Score:3, Informative)

        by Rycross (836649)
        I'd assume you'd "see" it by observing how it interacts with massive bodies around it, like planets, stars, gas clouds, etc.
        • You might "see" it as a gravitational lensing effect. Of course, that's far less sensational then claiming to see dark matter, as all you can really be sure of it that you're seeing a gravitational lensing effect (and this wouldn't really be news, as there have been a few gravitational lensing effects attributed to dark matter already).

          Seeing the gravitational effect on the massive bodies around it really wouldn't be news, as that's were all these dark matter theories have been coming from for years, with

      • how you see dark matter (Score:5, Informative)

        by TMB (70166) on Thursday May 10 2007, @05:54PM (#19076153)
        Given that the press conference isn't until May 15, I can't say for sure, but based on the brief blurb on the NASA website, it's almost certainly a gravitational lensing measurement.

        It's true that dark matter doesn't interact directly with light, but it does curve space (ie. generate gravity), which light travels through. So light feels the gravitational effect of dark matter, a phenomenon known as "gravitational lensing". Essentially, the images of background galaxies going through a concentration of dark matter become magnified and distorted.

        I don't know whether this is a strong lensing or weak lensing measurement. In strong lensing, the distortion is extreme and the images of the background get stretched into long tangential (and radial, though they're rarer) arcs like this [nasa.gov]. In the case of weak lensing, the distortion in any one image is small, but all images in a certain area are distorted coherently so you can statistically disentangle the signal.

        Given the distorted images of the background galaxies, you can determine what mass distribution was responsible for those distortions, thereby producing a "mass map". It appears that in this case (again, based on the brief blurb), the mass map shows some sort of ring-like structure that isn't seen at any other wavelength (which non-dark matter would produce).

        [TMB]
    • ... there's damned little you can do with Hubble (other than observe in the ultraviolet, and honestly, when was the last time you heard about that capability leading to some huge discovery?) that you can't do with a reasonably large terrestrial scope.

      Hubble is, by today's terrestrial standards, small. Its resolving power is limited, even in the relative vacuum of space, by the size of its mirror, the size, age and design of its instruments, and so on.

      Yes, Hubble finds stuff. But it doesn't find disproport

  • pic (Score:5, Funny)

    by antiaktiv (848995) on Thursday May 10 2007, @05:28PM (#19075851)
    Screenshot or it didn't happen!
  • Redmond Washington.

    Ok, mod me as troll. I deserve it.
  • Is it just me, or are humans getting better and better at science as time progresses?

    I mean, it seems likely that this would be the case, naturally. Nonetheless, it still strikes me.

    We predict dark matter exists, then we show it exists. It seems pretty much assured that we will even find out what it is made of. This discovery further cements this feeling in my mind.

    We figure there is a chemical of inheritance, we find DNA. We know there is a genome, we sequence it.

    Everything seems to be a big puzzle, and we seem to be getting faster and more accurate with putting these puzzles together.

    I feel fully confident in speculating, for instance, that we will solve the gene therapy issues in mere years. That we will have household humanoid robots by 2020 for under $50,000US. That we will enhance ourselves dramatically genetically and technologically by the end of the century.

    Has science always been this inexorable in it's progress?

    • Re:We Impress Me (Score:5, Insightful)

      by rts008 (812749) <rts008@hotmailFREEBSD.com minus bsd> on Thursday May 10 2007, @05:45PM (#19076065) Journal
      "Has science always been this inexorable in it's progress?"

      I don't beleive so. My take on it:

      Timely communication over wide areas has started the 'inexonerable progress'. Telegraph, railroads, telephones, 2-way radio,and now the internet have boosted progress dramatically as each were implemented.

      I may be wrong, but the concept you seem to be looking for is 'singularity'. It's happening quicker as time goes- like a snowball rolling downhill, it may not reach the bottom of the hill (true singularity), but it's headed that way.

    • Just don't piss them off! (Score:5, Funny)

      by iknownuttin (1099999) on Thursday May 10 2007, @05:45PM (#19076069)
      That we will have household humanoid robots by 2020 for under $50,000US. That we will enhance ourselves dramatically genetically and technologically by the end of the century.

      It could happen. But if we piss off those robots and the genetically engineered humans, they may band together and start an extermination program of us humans. Then we'd have to flee the planet in a fleet of ships while the robots pursue us. Of course, with the genetically engineered humans, they'll look like us and they'd be used as spies. Of course, there may be a comuter scientist who falls in love with one of them and helps the robots take us out. Then he'll go insane and start imagining his robot lover.

      I don't know if we really want to go there.

      • Don't be ridiculous!

        The most logical thing for them to do is to assimilate us all.

        RESISTANCE IS FUTILE!

    • Re:We Impress Me (Score:5, Informative)

      by smilindog2000 (907665) <bill@billrocks.org> on Thursday May 10 2007, @05:58PM (#19076223) Homepage
      There's an incredibly boring book, "Guns, Germs, and Steel", which I've mostly read (it's easier than reading the Old Testament!). The basic question posed in the first paragraph is "Why did Europe dominate the world?" He goes into fairly convincing arguments for why we are advancing faster and faster... technology feeds on itself in a positive feedback loop. He discounts the importance of the giants, like Newton, and focuses on the size of populations, the ease of communication of ideas and domesticated plants and animals between them. Technology is advancing at an unstoppable pace. The way it's going, it seems likely we'll either use it to kill ourselves, or birth a new race that we design... either biological through genetic manipulation, or electronic, or perhaps a combination of both.

      • it's easier than reading the Old Testament

        Well, that's a ringing endorsement for a book if I've ever heard one ;)

        I feel the same about our progress being both wonderful and dangerous. I am reading Asimovs' robot novels right now, and in a forward he made a deeply profound observation. Let me google it for accuracy...

        "Even as a youngster, I could not bring myself to believe that if knowledge presented danger, the solution was ignorance. To me, it always seemed that the solution had to be wisdom."

        I wonder if

      • He goes into fairly convincing arguments for why we are advancing faster and faster...

        But we aren't. Consider:

        My grandmother was born in 1884 and died in 1980. By the time she was my age (early forties) she had seen heavier than air flight used in warfare and commerce, the end of the age of sail, the invention, commercialisation and massive popularisation of radio, massive urban electrification, and the coming of the mass-produced automobile, just to name a few of the bigger changes. Oh yeah, and votes f
        • I feel that way sometimes. How cool would it have been to see the birth of powered flight? In 1907 (according to some spam I got), California had only 1.5 million people, and the average life expectancy was only 47 years old. But... I think we've had amazing advances, just not the sort you see flying overhead. We've built the Internet, and Moore's Law has held for nearly 50 years. My cell phone has more computational power than existed in the world in 1950. I was alive to see the first man set foot on
      • The book is only boring becuase Diamond makes his basic point in the first chapter, and then repeats the same damn point as the explanation for every cultural disparity that he cites as distinguishing between people from ancestral central Eurasia and, for example, ancestral Mexico.

        I'll ruin it for you: the point is that there were significantly more square miles of easily travelled arable land in the same climate zone accessible to people on the eurasian landmass than there was available to the Incas and Ma

    • We predict luminiferous aether (Score:5, Insightful)

      by vlad_petric (94134) on Thursday May 10 2007, @06:01PM (#19076253) Homepage
      We find no luminiferous aether.

      Not all scientific predictions are made equal.

      • Re:We predict luminiferous aether (Score:5, Insightful)

        by Lijemo (740145) on Thursday May 10 2007, @07:17PM (#19077081)

        "We find no luminiferous aether.
        Not all scientific predictions are made equal."

        that was a very useful prediction.

        We predicted luminous aether: it was a logical theory. We had good reason to believe that light was a wave, we had no reason to imagine that a wave could exist without a physical medium (air, water, etc.)

        It was a falsifiable theory.

        For a long time people tried to prove it, but measurements weren't sensitive enough. Finally, a sensitive enough experiment was developed, and it found-- nothing!

        This was far more useful than if they had found something.

        On discovering that the theory was wrong, they didn't try to argue that it was really still correct. They puzzled about what it could mean: how can a wave exist without a substance to wave through?

        Many incredibly significant scientific advances of the next few decades came out of this enigma. If there had been no luniniferous aether theory, there would have been no enigma, and perhaps many of these discoveries would not yet have come about.

        The usefulness of a theory is not in whether it's correct or not. The usefulness of a theory comes from what you learn while trying to discover whether or not it is correct.

    • $50,000 will buy you ONE chocolate-flavored corn syrup bar; unless you pay with Ameros then its only $5.

      • Re: (Score:2, Insightful)

        by amRadioHed (463061)
        I think you got it in the other way around. Specialization is result of progress. In the past it was possible to have a strong grasp of science in general, now there is so much to know it just can't be done.

  • More info (Score:5, Informative)

    by IWannaBeAnAC (653701) on Thursday May 10 2007, @05:44PM (#19076059)

    I was about to write a comment panning this submission, because apparantly a one-paragraph press release - that doesn't give much room for an intelligent discussion - was the only information on this discovery. But I did find an abstract for a talk given at the American Astronomical Society Meeting 209, which was held in January this year.

    Authors: Jee, Myungkook J.; Ford, H. C.; Illingworth, G. D.; White, R. L.; Broadhurst, T. J.; Coe, D. A.; Meurer, G. R.; van der Wel, A.; ACS Science Team We present a comprehensive mass reconstruction of the z = 0.4 rich galaxy cluster CL0024+17 from Advanced Camera for Surveys data, unifying both strongand weak-lensing constraints. The weak-lensing signal from a dense distribution of background galaxies ( 120 per arcmin^2) across the cluster enables the derivation of a high-resolution parameter-free mass map. The strongly-lensed objects tightly constrain the mass structure of the cluster inner region on an absolute scale, breaking the mass-sheet degeneracy. The mass reconstruction of CL0024+17 obtained in such a way is remarkable. It reveals a ring-like dark matter substructure at r 75" surrounding a soft, dense core at r<50". We interpret this peculiar sub-structure as the result of a high-speed line-of-sight collision of two massive clusters 1-2 Gyr ago. Such an event is also indicated by the cluster bimodal velocity distribution. Our numerical simulation with purely collisionless particles demonstrates that such density ripples can arise by radially expanding, decelerating particles that originally comprised the pre-collision cores. ACS was developed under NASA contract NAS5-32865, and this research was supported by NASA grant NAG5-7697.

    Unfortunately I can't find the paper itself. So there is slightly more info, but not much :-(

  • Typical (Score:4, Insightful)

    by malsdavis (542216) on Thursday May 10 2007, @05:58PM (#19076233)
    Why does the title read "Hubble Space Telescope Detects Ring of Dark Matter" when - as the first line of the summary states -, the HST actually only " may have finally found dark matter".

    "Has found" and "may have found" are very different things. I "may have" the lotto ticket which is going to win me millions of dollars in Saturday's draw; on the other hand, I may not. To pre-emptively state a conclusion before it has been made is foolish and extremely unscientific and simply not an accurate description.
  • ... to be too excited about this? I mean, scientists characterizes the behavior and name the thingie 'dark matter'. So even when they can conclusively say this ring-thing is made of such and such, but who knows how many type of 'dark matter' there really are.

  • Dark matter was already detected (Score:5, Informative)

    by Burz (138833) on Thursday May 10 2007, @06:16PM (#19076445) Journal
    ...last year: astronomers could see in the aftermath of two colliding galactic clusters. [sciam.com]

    The visible matter's momentum through space was impeded at quite a different rate than dark matter. This left four distinct zones of gravitational lensing, but only TWO were associated with visible matter. The other two were dark matter halos that had been separated from each galactic cluster.
    • Yes, but in that instance, there were two blobs of matter that slowed due to mutual interaction, gas pressure and whatnot, while the two associated blobs of dark matter shot off ahead. In this, it's a ring of dark matter.

      • Re: (Score:3, Insightful)

        by Abcd1234 (188840)
        So where's your published paper where you provide an alternative theory to explain galatic rotation?
  • "It seems dark-matter is nature's sex drug. It's like a perverted trail mix of penguin estrogen, penguine Viagra and Spanish penguin fly." - Paul, the space hippy

  • What is dark matter, any way? (Score:3, Interesting)

    by CokeJunky (51666) on Thursday May 10 2007, @07:35PM (#19077269)
    I had been under the impression that 'dark' matter was simply regular matter that we needed to exist to balance some equations, but that we couldn't see. Wouldn't this simply reduce the amount of dark matter by making it observable?

    Or is my impression that dark matter is stuff we can't see wrong? Is it actually supposed to be some exotic substance (with comic-book like powers)?

    • Re:What is dark matter, any way? (Score:5, Informative)

      by TMB (70166) on Thursday May 10 2007, @08:09PM (#19077497)
      Part of the confusion is that there are 2 separate concepts that both go by the name "dark matter".

      Dark matter in the broad sense is matter that we detect gravitationally but can't observe directly through any interaction with light (and if this measurement is from gravitational lensing, which I suspect, then it certainly falls into this catagory). We infer that it exists because the motions of stars and gas in galaxies, galaxies and hot gas in galaxy clusters, and the universe as a whole all act as though they are acting in the gravitational field produced by much more mass than what we can directly detect.

      Some fraction of this dark matter is normal ("baryonic") matter that just happens to be very difficult to detect due to its temperature and density... for example, a lot of it is diffuse gas at ~100000K, which is too cool to emit X-rays but too hot to emit much line radiation.

      However, from Big Bang nucleosynthesis calculations, we can estimate how much baryonic matter there is in the universe because the relative fractions of different isotopes of H, He, Li and Be are quite sensitive to the total amount of baryonic matter. And the total amount of matter required to account for the dynamics of the universe is about 6 times higher than the amount of baryons that Big Bang nucleosynthesis measurements indicate.

      Therefore, there must be non-baryonic dark matter too, made of exotic particles (or neutrinos, but there most likely aren't enough of those either). This is also sometimes just called "dark matter", which is confusing.

      Interestingly, galaxy clusters, like the one studied here, have most of their baryonic matter in the form of hot X-ray gas that is detectable... the density of baryonic matter we can detect within a galaxy cluster is about what you'd expect given the BBN calculations. So any dark matter in a galaxy cluster should be non-baryonic dark matter, which is why measurements like this are exciting.

      [TMB]
    • What, no Klingon jokes yet?

      • What, no Klingon jokes yet?
        Don't worry, I got it covered!

        KANG: De-lak DOH! Bosh-ta-jah Uranus!
        KODOS: jIyajbe'! Uranus-ghor tlhInganpu' tagh'a'?
        KANG: yIDoghQo'! ... nuq Daq 'oH puchp"e'?

        (My Klingonese is better than most people's Swahili...)
    • There's a 1% chance that I might have found that funny if you'd found a way to spell Uranus that actually contained the 4-letter word that's supposed to be the source of the humor.

    • Re: (Score:2, Funny)

      by IgLou (732042)
      I for one welcome our new Information Overloads...

    • I challenge you to find much more information on Dark Matter... that isn't purely speculative. Whining about the lack of information is even worse than the wildest of speculations. Get in the game!

      So far, it's all in the name; we can't really see it, ergo; dark. It has some sort of mass-effect in the universe, ergo; it matters. The only thing we can't agree on is what Dark Matter is. Let the speculations begin!

      1. - Maybe it's a Quantum Substance and we've already determined it's nature by giving it a na

      • Oooh I like Quantum Substance. Sort of like Vegemite but without the salt.

      • 1. - Maybe it's a Quantum Substance and we've already determined it's nature by giving it a name. If it ever gets in the way, just shine a light on it and it disappears!
        Are you saying there are... grues in space ???
    • There's a string of overhyped submissions here in the science section founded on a misreading of the source article.

      Contrary to what the submission seems imply, the Hubble did not directly detect dark matter, and you can pretty safely bet that it won't ever.

      What it did was find further evidence that dark matter exists. I don't think these media teleconferences are very rare, but they don't hold them every time somebody publishes a paper, either.

      My reading of the press conference announcement is tha

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