Most massive cosmic pileup ever seen

By Phil Plait | April 17, 2009 6:34 am

I recently posted about how cool it was on the Mythbusters when Adam and Jamie slammed a rocket sled into a car at 1000 km/hr.

Now take that collision and multiply it by a million billion gazillion. What you get is this:

Hubble+Chandra+Keck image of MACSJ0717.5+3745, a collision of four galaxy clusters.
Credit: NASA, ESA, CXC, C. Ma, H. Ebeling, and E. Barrett (University of Hawaii/IfA), et al., and STScI.

Holy Haleakala.

That’s quite an image. It’s of an object 5.4 billion light years away called MACSJ0717.5+3745, which is really just a catalog number and a coordinate on the sky, so it’s not nearly as awesome sounding as what it is: a massive collision between four separate galaxy clusters!

Almost all galaxies reside in a group of some sort. The Milky Way is part of the local group, a few dozen galaxies, mostly dinky ones, of which we’re actually the largest. And our little enclave is in the suburbs of the Virgo cluster, a much larger aggregation of hundreds of galaxies. These clusters move around, and sometimes they collide (check out the Bullet Cluster, for example, for a fantastic example of this kind of collision, and how it gave us proof positive of the existence of dark matter).

But four clusters, colliding all at the same time? Wow!

The image is a composite of Hubble (visible light image) and Chandra (which sees high-energy X-rays) data. So what are we looking at?

First off, almost everything you see in that image is a galaxy (grab the big or the ginormous versions of the image for some fun). Foreground stars are the dots with the four spikes going through them (that’s an artifact of the camera used by Hubble, and is most obvious in point sources, and almost non-existent in extended objects like galaxies). So right away you get an idea of what a cluster of galaxies is like… and what a disaster a collision between four of them can be!

The clusters are all moving through space at incredibly high speed, many dozens of kilometers per second. In a vast collision like this one, the galaxies may physically smack into one another, though I suspect that’s not as common as you might think; there is still way more empty space in a cluster than there are galaxies.

Still, the gas between galaxies is spread out over hundreds of thousands or even millions of light years, well beyond the galaxies themselves. So this intercluster gas will indeed collide at high speed, causing it to heat up to millions of degrees and glow in X-rays. In the image, that’s shown as the diffuse material colored purple-red (lowest energy gas) to blue (highest energy or hottest gas). In fact, by mapping the hottest parts of the gas — where the light is brightest and bluest — and comparing that to the positions of the galaxies, astronomers were able to see that there are four distinct clusters in this train wreck. Also, in the collisions the galaxies just keep moving, while the gas slows down as it collides, so comparing the positions of the gas and galaxies the direction of the clusters was found as well. The speed can be found by taking spectra of the galaxies, which was done using the giant Keck 10-meter telescope in Hawaii. That also helps track which galaxy belongs to which cluster, assuming the galaxies in a given cluster are moving at roughly the same speed.

All in all, I can see that this cluster will keep astronomers busy for a long, long time. Studying it will tell us a lot about how intergalactic gas behaves, possibly about the nature of dark matter (which cannot be seen in this image — hello, it’s dark matter — but certainly profoundly affects the way this system behaves), and also just plain old what happens when a few hundred galaxies slam into each other across the depths of space.

CATEGORIZED UNDER: Astronomy, Pretty pictures, Science

Comments (65)

Links to this Post

  1. Collision d’amas « Dr. Goulu | April 17, 2009
  2. Most Massive Cosmic Pile up Ever Seen « Athena | October 11, 2009
  1. QUASAR

    That’s beautiful!

  2. philippec

    If the interstellar gas is heated up to millions of degrees, does this rule out the possibility of planets forming in any of those galaxies? Don,t planets need some kind of cool environment?

  3. Ariane

    Geez, the universe is an awesomely amazing place! Looking at pictures like this you can’t help but feel humbled (and a wee bit insignificant).
    Looking at all these tiny little dots/smudges of light, many of which represent incomprehensibly huge galaxies, kinda bows my mind.

  4. man, I realize this is an argument from incredulity…

    but I look at a picture like that, and know that this is one tiny fraction of the universe, and that each of those galaxies has hordes of stars, and each star likely has a bunch of planets….and think: there is no way that we are alone in this universe.

  5. Wow!
    What a great demonstration of the Hyneman/Savage effect!
    Next stop Stockholm!

  6. scotth

    This is another one of those pieces of discovery that when I contemplate all the details of what is known, how far it is away, how big, how we figured it out……

    My poor little brain just about locks up, but in such a good way. Just wow.

    The feeling of awe, the numinous, and connectedness is heart-melting. It takes a little education and work to be prepared to understand and feel it. A pity that so many religious people think that they have monopoly on this market.

  7. Andrew

    The intra-cluster medium is a bit like the solar corona – the gas is very hot but it is also very diffuse – perhaps 1,000 particles per cubic metre on average at temperatures of around ten million Kelvin (hotter denser in the middle and cooler and more diffuse further out). But, given the size of these things, there is (millions of solar) masses and masses of it. If the gas is floating around as a plasma between the cluster galaxies, it won’t be able to collapse to form stars and planets any time soon (although radiating away in the x-ray will cool it down and make it collapse relatively quickly – within perhaps billion years) but there are already stars, and presumably planets, inside the galaxies already that would have formed earlier.

  8. Maxwell

    @phillippec

    Actually, in interstellar space, the density of gas in outrageously small (I think around a particle per cubic meter or centimeter, don’t remember off the top of my head). To heat it to that level requires much less energy than you think, that’s why the temperatures are so high. Also, since the medium is so dispersed, there’s nowhere near enough gas to form something under it’s own gravity.

    tl; dr – Planets/stars almost all form in galaxies, not in the intergalactic medium.

  9. Maxwell

    If you look at the center of the large image, there’s two very round, small, smooth purple blobs at 1 o’clock and 10 o’clock. Anyone know what these are?

  10. chili

    Absolutely awesome!!!
    Of course this is what what it looked like 5.4 billion years ago. I have to wonder what it looks like now. Too bad we can’t travel faster than light and get to this region to see what the result of the collision has manifested. By now things must have settled into some wondrous new shape or configuration.
    Anyone figured out how to generate a wormhole yet??? ;-)

  11. KAAAAAAAAAAAABBBLOOOOOOOOOOOOOOIIIIIIIEEEEEEEEE!

  12. Flying sardines

    Now take that collision and multiply it by a million billion gazillion.

    Well I would *if* I could recall exactly how many zeroes there are in a gazillion … ! ;-)

    1 gazillion = 1 followed by ???? 0’s???

    THX anyway Phil – great article! :-)

  13. BJN

    Slam into each other? Can swarms of bees or dust-devils slam into each other? Sure there are collisions of individual bees or sand grains when swarms and vortices run into each other. And I’m sure there’s plenty of disruption of the moving structure of stars and some stellar slamming when galaxies intersect, but “slam” implies that galaxies are much more solid than they really are.

  14. Flying sardines

    It’s of an object 5.4 billion light years away called MACSJ0717.5+3745, which is really just a catalog [sic] number and a coordinate on the sky, so it’s not nearly as awesome sounding as what it is: a massive collision between four separate galaxy clusters!

    Yes indeed.
    Can we please call it something other than just MACSJ0717.5+3745 please!?

    Doesn’t this thing deserve a decent name!?

    Besides how do you pronounce “MACSJ0717.5+3745″ anyway? ;-)

    See catalogue names like this really don’t help astronomy’s cause.
    Catalogue names are one of my pet gripes about astronomy, come on, lets give all these wonderful objects a pronouncable, halfway worthwhile tag for pity’s sake eh?! :-(

    Might I propose the Kaboom or the Smash-up clusters? ;-)

  15. scotth

    @Flying sardines, I think Smash-up cluster is great. Seconded. (like anyone will care).

  16. Todd W.

    How about the amethyst cluster?

  17. Dean

    That area must really suck.

  18. Brian

    The Titanic-Inferno-Monster-Krusher kluster!

  19. A gazillion is a one followed by a gazillion zeroes. Duh.

  20. Joe N.

    @BJN

    the swarm of bees can most definitely slam if it flies in the shape of a fist, mallet, or another blunt object.

  21. Sundance

    I have to say it… nobody else has yet… can’t…resist…!

    Where’s the Kaboom? There was supposed to be an Earth-shattering Kaboom?

    @Flyingsardines: Maybe that’s it. We should call it the Eludium Plu-36 Explosive Space Modulator cluster(s)

  22. LCH

    So cool! What’s happening to the life forms who live in those Galaxies? (I’m reading Death from the Skies! right now and am feeling pessimistic :) )

  23. Torbjörn Larsson, OM

    I, for one, bow to our Galactic Overlords.

  24. jeri meaux

    Hey Phil–shouldn’t “dark” matter technically be called “clear” matter?

  25. The Constant

    Dark sounds more cool, more mysterious, more forboding and is fashionable at any occassion. Clear may be a bit risque.

  26. Gary

    @Flying sardines I agree, it needs a much more intensely awesome name. How about the Firedagger Cluster? We totally need to get the League of Awesomeness involved in the naming of astronomical finds.

    (In all seriousness though, the Amethyst Cluster is a good suggestion, I like that one.)

  27. Matt

    Invisible Pink Matter, perhaps?

  28. John Swindle

    Beautiful images like this leave me wondering about so many things… the unimaginable distances and sizes, the cold-hearted stretch of time, as light and x-ray energies traveled to our neighborhood… and I wonder how many lives, perhaps similar to our own in some way, are destroyed in such events. Beautiful, sure. But sobering, too.

  29. Todd W.

    Hmm…looking at it again, and since it’s more than one cluster involved, I’d like to change my proposed name from Amethyst Cluster to Amethyst Spindle. It kinda looks like a spiraling spindle of amethyst, to me.

  30. Mark

    Maxwell – The purple blobs probably are galaxies giving off relatively low energy X-rays. What you see in the picture is an artifact of the merging of Hubble and Chandra’s images.

  31. - “How many clusters do you see?”

    -“There are four clusters!”

  32. MarkAH

    While the four cluster collision is cool, I more drawn to the background galaxies. Looks like there are more than a few binary(?) galaxies there and some seem to be in the process os eating one another. Of course is may be perspective, but, the pair at the bottom of the picture at about the 5 o’clock position has something going on there.

    Unfortunately to my untrained eye the main subject of the picture looks like a big purple blur. :(

  33. Torbjörn Larsson, OM

    Speaking of pileups and being seen, Kepler threw its cover a few days ago, achieved first light and now features a humongous star field view on its web pages. “Kepler’s Diamond Mine of Stars” “contains an estimated 4.5 million stars”. It works!

    So it’s not a million billion gazillion stars. But there will likely be tens of thousands of planets among the hundreds of thousands of candidate stars! When will we see the first Earth analog?

  34. @BA “Studying it will tell us a lot about how intergalactic gas behaves, possibly about the nature of dark matter”

    Dark matter? O.K. Expect a horde of wild EUers in 1, 2, 3,…

  35. Cindy

    When I mentioned to my husband about the cool picture of 4 clusters colliding, he commented “Gee, that must slow traffic down a bit”. Sigh. Biologists!

  36. john hart

    When I see a picture of a galaxy(ies) I want to know how it compares to our own the Milky Way. A picture like this would be much more meaningful if I could scroll over each galaxy I put my pointer on and up would pop a +1-10 on how much bigger or smaller that galaxy is compared to our own.

  37. # Cindy Says:
    When I mentioned to my husband about the cool picture of 4 clusters colliding, he commented “Gee, that must slow traffic down a bit”. Sigh. Biologists!

    At least he didn’t ask if anyone was cited for failure to yield…..

    J/P=?

  38. Wow man thats really awesome. i find space to always be very interesting to me and like looking at pictures for hours. To think there is so much more out there!!

  39. K

    this image looks so wwierd in high res..almost looks fake..

  40. Na

    It may be me, but I prefer the name Amethyst Dreidel… it kind of looks like one to me. ;)

  41. karthik

    a never ending pursuit to the answer of all time favourite question all over the planet…ARE WE ALONE???…might be answered soon enough!!!
    get the extra large version of the pic here…
    http://hubblesite.org/newscenter/archive/releases/2009/17/image/a/format/xlarge_web/

  42. enigma3535

    This post reminded me of a conundrum I have had for a while. How do the literal creationists explain away photos like these of light emitted billions of years ago? Does anyone know their argument on this point?

  43. I too am wondering about the lifeforms that must have lived there, considering all the planets available. Sixty years ago the universe was considered more or less static. Now we know it’s a beautiful, violent, and dangerous place. Maybe that’s why religous people can’t give up their need for something omnipotent to hold onto. The rest of us just have to take a deep breath and roll with the punches (or collisions).

  44. @ enigma:

    Light moved at different speeds in the past. Quote, unquote.

  45. MKULKTRA

    enigma3535 , the explanation from Creationists, if you can believe this, is that God already set the light from those galaxies in motion at Creation toward any observer and is another test of ‘Faith’ to the hapless observer. Gifted with the tools to discern and understand from reason, but then foolishly tricked by such ploys as fossils, carbon dating, geology and astronomy. What kind of God is that?

    “You’ve got your Jesus, I’ve got my Space.”
    -Filter

  46. K

    Anyone look at the high-res tiff image?

    Is their any way to confirm these pics are real at all?

  47. I looked at this image and suddenly felt very, inconsequentially small.

    I guess it’s a good thing I wasn’t strapped into a machine that shows me my place in the universe based on a piece of fairy cake.

  48. I agree with the previous commemts. A cosmic phenomenon of this magnitude, so majestic and stunningly beautiful, deserves a more befitting name than the mere jumble of letters and digits assigned to it and quite unintelligible to most. The “Amethyst Cluster” is certainly a good one.
    Since hundreds of galaxies appear to be hurtling or swirling into some kind of unimaginably violent cosmic melting pot, perhaps another suggestion might be (if the colour were more purplish), the “Great Magenta Maelstrom” or “Great Sapphire Whirlpool” might even be acceptable. The IAU will decide on a name and there are no prizes for the winner. I would imagine there must be some super-sized black hole monster in the midst of this galactic train-smash, powerful enough to gravitationally ensnare so many island universes. Has the focal point or collision epicentre been identified yet?

    Graham Ball (South Africa)

  49. WMDKitty

    ::stares in silence::

  50. DrFlimmer

    @ graham ball

    I would imagine there must be some super-sized black hole monster in the midst of this galactic train-smash, powerful enough to gravitationally ensnare so many island universes.

    Sadly, not ;) . It’s just the attraction of the four clusters that drives them together…

  51. Is their any way to confirm these pics are real at all?

    They are fake.

    The way to tell is that they depict something that occurred more than 6,000 years ago.

  52. Flying sardines

    Are you being a Poe (satirist that ‘shard topick from being “for real”) there, Doug Watts?

    What does real mean in your context anyway?

    No false colour? No processing? As the eye alone would see it?

    Or just showing a real event and objects as they were X billions of years ago? (The light from the Smash-up clusters as they are still being in transit.)

    Hang on what’s this about 6,000 years?! Aha! I call Poe. ;-)

  53. Flying sardines

    MKULKTRA : (April 18th, 2009 at 11:36 am)

    enigma3535 , the explanation from Creationists, if you can believe this, is that God already set the light from those galaxies in motion at Creation toward any observer and is another test of ‘Faith’ to the hapless observer. Gifted with the tools to discern and understand from reason, but then foolishly tricked by such ploys as fossils, carbon dating, geology and astronomy. What kind of God is that?

    Aha again! I’m NOT myself even a creationist but I’ve just been able to make perhaps the greatest ever ID “tehory” breakthrough! The idenity ofthe goDesigner isnow clear :

    It is Loki the Norse Trickster God!!! ;-)

    … Or wait maybe also the trickster God Pan or was it Hermes and maybe Coyote?

    Ah well, that’s still narrowed it down a little – it certainly rules out Yahweh /Jehovah /JesusHolySpiritFatherMary – that postulated deity was meant to be much more honest and open and far less deceptive and tricky right? ;-)

    Hmm .. maybe the first thing you see after death is a giant :

    YOU”VE BEEN PUNKD!

    sign? ;-)

  54. Flying sardines

    That’s meant to read :

    The identity of the unknown god-Designer is now clear : Loki theViking Trickster god!!

  55. BeinSilly

    Sadly, not . It’s just the attraction of the four clusters that drives them together…

    Their attraction?

    Awwww .. They’re in Lurve! <3 ;-)

  56. I looked at this image and suddenly felt very, inconsequentially small.

    Odd.

    I have the exact opposite reaction to images such as this. We are every bit a part of that vastness as the stars and galaxies themselves, and, unlike them, we are aware of the fact.

    They may be huge, but galaxies can’t paint a Guernica or write an Odyssey. Not without us, anyway.

  57. # BeinSilly Says:
    Sadly, not . It’s just the attraction of the four clusters that drives them together…
    Their attraction?
    Awwww .. They’re in Lurve! <3 ;-)

    Yes, but are they opposite(?) sexes? Or are we dealing with a threat to Traditional Galactic Collisions?

    %)

    J/P=?

  58. Nick

    So, what would happen to a single planet in one of those galaxies? Would it probably be left mostly unaffected since there is still so much empty space in there, or would it be fried to a crisp by the super-heated gas, or what? Basically, are we looking at a picture of the possible extermination of countless hypothetical civilizations?

  59. Daniel

    Triple A card anyone?

  60. clyde

    What is expected? If the gas slowes, and the clusters maintain speed, will the gas be striped off and left behind? Pull my finger.

  61. DrFlimmer

    @ Nick:

    I guess the odds for one specific planet to be affected are quite low. On the other hand: There are many planets – so one planet or another will be screwed.

    @ clyde:

    If there is a reason for the gas to slow down: Yes. But what would be the reason?

  62. clyde

    @ DrFlimmer:
    In the text, it was mentioned that the gasses were smashing together and causing the purple-red to the blue or higher energy and slowing. The galaxies maintained their speed. If so, and the gases were left behind, could that cloud become a star generator? Or, with nothing better to do, would it let gravity suck it back to the clusters?

  63. DrFlimmer

    Since the gas clouds smack together almost at the same place as the galaxies, they will more or less stay at the same spot, I guess.

    A star generator? Hm. Since this gas is REALLY thin (probably 1 particle per m^3) and the gas is very hot at the moment, it is very unlikely. If the gas has a chance to cool down (well, extreamly down…) it could lead to gravitational collapses. But this unlike scenario would happen in a very far future, it at all.

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