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Huge news about a huge structure

  1. Aug 6, 2015 #1
    I just saw the following news and thought this could have quite an impact on our current models and views of the Universe:



    The GRBs that make up the newly discovered ring were observed using a variety of space- and ground-based observatories (the sample is listed in the Gamma Ray Burst Online Index). They appear to be at very similar distances from us – around 7 billion light years – in a circle 36° across on the sky, or more than 70 times the diameter of the Full Moon. This implies that the ring is more than 5 billion light years across, and according to Prof Balazs there is only a 1 in 20,000 probability of the GRBs being in this distribution by chance.

    Most current models indicate that the structure of the cosmos is uniform on the largest scales. This ‘Cosmological Principle’ is backed up by observations of the early universe and its microwave background signature, seen by the WMAP and Planck satellites. Other recent results and this new discovery challenge the principle, which sets a theoretical limit of 1.2 billion light years for the largest structures. The newly discovered ring is almost five times as large.

    “If the ring represents a real spatial structure, then it has to be seen nearly face-on because of the small variations of GRB distances around the object's centre. The ring could though instead be a projection of a sphere, where the GRBs all occurred within a 250 million year period, a short timescale compared with the age of the universe.”

    A spheroidal ring projection would mirror the strings of clusters of galaxies seen to surround voids in the universe; voids and string-like formations are seen and predicted by many models of the cosmos. The newly discovered ring is however at least ten times larger than known voids.

    Prof Balazs comments: “If we are right, this structure contradicts the current models of the universe. It was a huge surprise to find something this big – and we still don’t quite understand how it came to exist at all.”

    The team now want to find out more about the ring, and establish whether the known processes for galaxy formation and large scale structure could have led to its creation, or if astronomers need to radically revise their theories of the evolution of the cosmos.

    https://www.ras.org.uk/news-and-pre...rs-across-the-largest-feature-in-the-universe

    http://www.mnn.com/earth-matters/sp...-structure-one-ninth-size-observable-universe
     
  2. jcsd
  3. Aug 6, 2015 #2

    DEvens

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    This is very interesting. When I hear researchers saying things like "contradicts the current models" I am very interested. It suggests we are about to learn something very new.

    On the other hand, when it comes to cosmological issues, I have learned to be pretty cautious. It is a good idea to watch this with interest and see what people can discover about it over the next few years.
     
  4. Aug 6, 2015 #3
    DEvans I agree.
    Actually I am so cautious that I am not willing to go 100% without any reservations on any large scale Cosmological theory at this time.
    New data is still coming in as we see can here.
     
    Last edited: Aug 6, 2015
  5. Aug 6, 2015 #4

    marcus

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    The technical article published in MNRAS (online 24 July 2015) is
    http://arxiv.org/abs/1507.00675
    A giant ring-like structure at 0.78<z<0.86 displayed by GRBs
    L. G. Balazs, Z. Bagoly, J. E. Hakkila, I. Horvath, J. Kobori, I. Racz, L. V.Toth
    (Submitted on 2 Jul 2015)
    According to the cosmological principle, Universal large-scale structure is homogeneous and isotropic. The observable Universe, however, shows complex structures even on very large scales. The recent discoveries of structures significantly exceeding the transition scale of 370 Mpc pose a challenge to the cosmological principle.
    We report here the discovery of the largest regular formation in the observable Universe; a ring with a diameter of 1720 Mpc, displayed by 9 gamma ray bursts (GRBs), exceeding by a factor of five the transition scale to the homogeneous and isotropic distribution. The ring has a major diameter of 43o and a minor diameter of 30o at a distance of 2770 Mpc in the 0.78<z<0.86 redshift range, with a probability of 2×10−6 of being the result of a random fluctuation in the GRB count rate.
    Evidence suggests that this feature is the projection of a shell onto the plane of the sky. Voids and string-like formations are common outcomes of large-scale structure. However, these structures have maximum sizes of 150 Mpc, which are an order of magnitude smaller than the observed GRB ring diameter. Evidence in support of the shell interpretation requires that temporal information of the transient GRBs be included in the analysis.
    This ring-shaped feature is large enough to contradict the cosmological principle. The physical mechanism responsible for causing it is unknown.
    13 pages, 8 figures and 4 tables
    ===========================
    It isn't clear how they came up with the "one in a million" unlikelihood. When you have brief random flashes all over the sky all the time, presumably every now and again you are going to see some geometric pattern in them.
    I think what you say is wise about taking a wait-and-see attitude.
     
    Last edited: Aug 6, 2015
  6. Aug 6, 2015 #5

    marcus

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    On page 7 of the paper:
    "GRBs are short-lived transient phenomena. The GRBs that compose the ring, along with their redshifts, were collected over a period of about ten years."
     
  7. Aug 6, 2015 #6

    Chronos

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    Perhaps Im missing something, but, the paper looks like an exercise in guilt by association. Is it really one in a million odds against 9 GRB's at about the same distance occuring across a large area of sky over a ten year period? I'm pretty sure you could find a dozen or so galaxies at near identical redshift in the Hubble ultra deep field or a dozen supernoval in the SNLS catalog at the same redshift. What would that prove? Didn't Penrose get fileted for claiming to find 'circles in the sky' that others deemed a flock of cloud dragons? Strong claims require strong evidence and this one looks like it falls a bit short.
     
  8. Aug 6, 2015 #7

    marcus

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    Penrose was a big target so got more pushback. These authors are smaller fry, more likely to just be ignored. If you look back Horvath and friends have been making a business of putting out this kind of message for some time, I don't recall how many papers, without getting much professional notice AFAICS. have to go.
     
  9. Aug 6, 2015 #8

    Bandersnatch

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    This paper cites Clowes et al. (2013) as an example of large-scale structure discovery. Wasn't it pretty much shot down in subsequent critical papers as essentially seeing patterns in the noise?
     
  10. Aug 6, 2015 #9

    Chalnoth

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    That's the way these things usually go. Doing the statistics correctly for finding anomalies is hard, and a lot of the scientists who try mess it up.

    This is one big reason why the more common approach is to try to test a very specific prediction, instead of just looking for something that is different.
     
  11. Aug 6, 2015 #10

    Chronos

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  12. Aug 6, 2015 #11

    ohwilleke

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    Agreed. This is a case where there different between expected frequency with and without a look elsewhere effect is huge. The notion that there ought to be at least one arguably structure out of all possible arguable structures that has a 2*10^-6 probability standing alone somewhere in the CMB with a very loose definition of arguable structure, doesn't seem all that remarkable to me. Maybe from some other perspective at some arbitrary scale, there's something that looks like a sine wave with nine humps and a triangle at the end that you could call a giant dragon shape. We are a people who invented roughly 88 constellations (plus some named sub-constellations) of purely random star arrangements that have no genuine connection to proximity of stars to each other as a result of their varying distances from us. Surely, we are clever enough to find one more roughly circle somewhere made out of something in the CMB sky of some arbitrary size.
     
  13. Aug 10, 2015 #12

    mfb

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    "Structure"

    They give a 5E-4 probability to find such a cluster. Looking at figure 3, it seems to be the local probability. The probability to find a cluster at this specific region in space! At ~40 different distances and ~40 different regions in the sky (both guessed from the plots) we have 1600 different chances to hit a 1 in a 2000 chance. This is not surprising at all.
    I really hope I misunderstood plot 3, otherwise the paper is not worth the paper it might get printed onto.

    The appendix is even worse. I didn't check the numbers, but the approach is clearly designed to give some large and small numbers that have no relevance to the observation at all. They just look cool.

    Even if we ignore the look-elsewhere-effect and the details of the mathematical analysis: what kind of structure would that be? The observed gamma ray bursts happened with more than hundred million years between them (as the distances of the galaxies are different). We would need a shell-like structure that leads to a higher GRB rate for hundreds of millions of years - only in this single shell, nowhere else in the universe. And for some reason this structure influences the rate of GRB only, not the galaxy formation itself, not the CMB passing through it or anything else. A ring instead of a sphere would be even more odd.
    Magic?
     
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