back to article Astroboffins peep at the largest orgy of galaxies banging into each other

Astronomers have spotted a whopping 14 galaxies on the verge of merging to create what could be the densest and most massive galactic cluster in the universe. The discovery was made after the South Pole Telescope in Antarctica scanned the night sky and found a population of rare, extremely bright objects nicknamed SPT2349-56. …

  1. Pascal Monett Silver badge

    "as it is unlikely that there are more than about 16 such objects across the entire sky"

    Cue more research in the coming months revealing that such superclusters are a one-in-a-million chance happening nine times out of ten.

    1. B83
      Pint

      Re: "as it is unlikely that there are more than about 16 such objects across the entire sky"

      Yeah just like the GoldiLocks planets.

      You used to get told there would be hardly any but when there are more stars than there are grains of sand on all the beaches on Earth. There might be more GoldiLocks scenarios that people realise.

      Dr. Jason Marshall, aka, the Math Dude. According to Jason, there about 700 trillion cubic meters of beach of Earth, and that works out to around 5 sextillion grains of sand.

      (https://www.universetoday.com/106725/are-there-more-grains-of-sand-than-stars/)

      I don't want to sound like I am knocking the research but I am sure its quite a big place out there.

  2. Rich 11

    Long, long ago in a galaxy far, far away...

    All 14 galaxies will eventually spiral into one another and merge to create one gigantic elliptical galaxy.

    All 14 galaxies did eventually spiral into one another and merged to create one gigantic elliptical galaxy.

    We'll just have to hang around for another half a billion years or so to confirm that it happened.

    1. Mark 85

      Re: Long, long ago in a galaxy far, far away...

      Might this be the first sign that the universe is starting to collapse back into the one rather large ball of matter as it was just before the big bang? And so it begins.....

    2. Daniel von Asmuth
      Alien

      Re: Long, long ago in a galaxy far, far away...

      All 14 galaxies will eventually spiral into one another and merge to create one gigantic elliptical galaxy.

      I wonder how long this 'eventually' may take.

  3. Michael H.F. Wilkinson Silver badge
    Coat

    Galactic rush hour pile-up?

    Oy! Watch where you drive that galaxy!

    Sorry, couldn't resist.

    I'll get me coat. The one with Arp's Catalogue of Peculiar Galaxies in the pocket, please

  4. Primus Secundus Tertius

    Number query

    "Miller estimated that the total mass of the elliptical galaxy would be about 100 billion solar masses."

    I thought there were some 10**11 stars in our own galaxy. Some of those are rather small, of course. The remote one may therefore be more massive than us, but not to the extent that justifies headlines.

    1. John Mangan

      Re: Number query

      I wondered about that as well. With 14 galaxies colliding I would have expected something well north of a trillion solar masses?

      UPDATE: Quick Google shows Milky Way estimated mass to be ~ 700 billion solar masses.

      1. John Mangan

        Re: Number query

        UPDATe update: looking, briefly, at the paper and skimming the table of cluster properties seems to show that the various entities range in size from ~120 billion solar masses down to ~ 2 billion solar masses. So all significantly smaller than the Milky Way. The total mass is around 670 billion Solar Masses and I presume some would escape during the spiralling colliding and gravitational distortions.

        So, now, I don't understand the claim that this is such an impressive object unless it is purely in reference to the epoch in which it is found rather than the wider observed universe?

        Anyone?

        1. Rich 11

          Re: Number query

          unless it is purely in reference to the epoch in which it is found

          That's my reading of it.

    2. Cuddles

      Re: Number query

      "I thought there were some 10**11 stars in our own galaxy. Some of those are rather small, of course. The remote one may therefore be more massive than us, but not to the extent that justifies headlines."

      I think the confusion comes from the difference between the mass of gas, and the total mass (which includes a significant portion of dark matter), and the difference between the colliding galaxies and the larger cluster. The Milky Way has a total mass somewhere between 10^11 and 10^12, which is close to the mass of gas in this cluster, but significantly less than the estimated total mass in the region of 10^13. It's further noted that while this is the mass of the 14 galaxies seen colliding, the theory is that this will form the core of a cluster, not be the whole thing itself, with the total mass being somewhere around 10^15 and making it the one of the largest (although probably not quite the largest) galactic clusters known (shown in figure 2 of the paper).

      1. John Mangan

        Re: Number query

        Yes, it looks like the 10^15 solar masses is an estimate of what it would look like 'now' (z=0) after however many billion years of development.

        It does say that the estimate has many uncertainties in it.

  5. The Nazz

    The odd random thought ....

    If we (ie the boffins) are starting to see the light from stars 13bn light years away, and given that most stars are spherical(ish) then ....

    how far out the other side does the light shine?

    (Note to self : don't ask into what.)

    1. Daniel von Asmuth

      Re: The odd random thought ....

      Also 13 bn light years to the other side given the speed of light is constant and the universe roughly homogeneous.

      (Note to self: don't ask who are watching)

    2. Christopher Blackmore

      Re: The odd random thought ....

      Don't assume space is straight...

    3. Cuddles

      Re: The odd random thought ....

      "how far out the other side does the light shine?"

      The same distance. While there are still questions about exactly how big and what shape the universe is, there are a variety of limits we can put on it given what we can see. While we can only see light that left things around 13 billion years ago (which actually equates to around 46 billion light years distance, due to the expansion of the universe), we can infer what is happening some distance beyond that through observations of the things we can see - the furthest things we can see would behave differently if there was a sudden edge just past them, or if things were wrapping back around, compared with if the universe carries on in a similar manner. Based on observations of the CMBR, it appears the universe must be at least 78 billion light years in diameter. Of course, most theories say it's actually somewhere between much bigger and infinite, but it may well be impossible to actually get evidence beyond a certain point.

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