Obese, gluttonous, and cannibalistic is no way to go through life, son

By Phil Plait | May 17, 2010 9:30 am

Astronomers have found a bloated, massive galaxy that may be a record-breaker: the most massive galaxy in the near Universe. The mass isn’t exactly clear, but it may be 13 trillion times the mass of the Sun!* That’s easily twenty times the mass of the Milky Way!

Here’s the guilty party:

gemini_abell_3827

OOoo, purty. Click to record-breakingly-massively embiggen.

That’s an image from the 8-meter Gemini South telescope in Chile, and it shows the cluster Abell 3827, a 1.4 billion-light-year-distant collection of hundreds of galaxies all bound together by their own gravity. It’s a pretty rich cluster as they go. Many like it have one big galaxy in the core, called the central dominant galaxy (or sometimes cD for short), and it’s usually a few times bigger than any other galaxy in the cluster.

In the case of Abell 3827, though, the cD — called ESO 146-IG 005 — is out of control. The Milky Way is considered a big galaxy, and has maybe 400 billion times the mass of the Sun in total, but 146-IG is hugely bigger, swollen and ginormous. It’s far more massive than any other galaxy we’ve seen out to that distance. That glow you see in the center of the cluster is just from 146-IG all by its lone self, and it dominates the entire core of the cluster.

So how do we know this, and how did it get so big?

abell3827_nucleiHow it got this way is clear from a close-up of the galaxy itself, shown on the right. As you can see, the galaxy has more than one nucleus! In this zoom, there are two foreground stars marked with an S, so you can ignore those. The other five objects are all galaxy cores, which to an astronomer is like a smoking gun: ESO 146-IG 005 has been very busy lately, eating other, smaller galaxies. Yup. It’s a cannibal.

We have seen this countless times. Heck, the Milky Way is in the final stages of devouring several smaller galaxies, but in our case the process is almost complete. The nuclei of galaxies are hard to digest, so to speak: the stars are tightly bound to the core by their gravity, so it’s hard for the larger galaxy to absorb them all. It takes time. 146-IG clearly has been gulping down a lot of the other cluster members, and this is why it’s so massive. We think that most large galaxies in the Universe grew to their present size by eating other galaxies.

So we know it’s massive. But how do we know how massive?

Take a look at that zoom picture again. See that little arc of light to the lower left? That is a gravitational lens, an image of a distant galaxy whose light has been distorted by the gravity from 146-IG. When light passes near a massive object, its path gets bent, like a car driving on a curved, banked road. The mass of the intervening galaxy acts like a lens, hence the term, and it can have all sorts of weird effects on the light.

The amount of distortion depends on lots of things, including the mass of the lensing galaxy, in this case 146-IG. There are other lensed background galaxies in the image as well, and the astronomers used those to get the mass of 146-IG. However, it’s not all that straightforward; it’s hard to separate out the mass of the galaxy from the cluster itself, and from gas and such inside the cluster that may not be part of the central galaxy. So all we get is an estimate.

Worse, the astronomers used a second method to find the galaxy mass, and got a much different amount. Gas inside a cluster gets heated as it moves around and falls to the center. The amount of heating (measured by looking at the X-rays emitted by the extremely hot gas) depends on the mass of the cluster, and can be used to estimate how much stuff is there. The astronomers found an "X-ray mass" only a tenth of the mass found using the gravitational lens method. There could be any number of reasons this could happen: the models for the gas assume it’s spherical and smooth when it may be neither, for example.

But either way, ESO 146-IG 005 is still one of if not the most massive galaxy in the nearby cosmos. It’s much larger than our own galaxy, by a comfortable amount. In the case of our galaxy, we ran out of smaller galaxies to eat, whereas 146-IG is basically still standing in the kitchen with the refrigerator door open.

It makes me glad the Milky Way is nowhere near that cluster. Sure, we got to our present size by eating other galaxies, but the time of unrestrained gluttony is in the past, and that’s good. It would make our neighborhood something less than the calm, peaceful place it is now. Having undigested galactic nuclei flying around, quadrillions of tons of gas and dust sloshing hither and yon, and all that million degree X-ray emitting gas sitting out there… that can’t be good for property values.



*Note that the press release linked says the mass may be 30 trillion times the Sun’s mass. This is incorrect; that’s the total mass of the cluster core, and may include stuff that’s not part of the galaxy itself.

CATEGORIZED UNDER: Astronomy, Cool stuff, Pretty pictures

Comments (44)

  1. Kendall

    It seems to me a bit of a rush to call it a galaxy until those galactic cores are truly combined. Of course, it’s 1.4 billion light years away, so maybe they are combined by now….

  2. Gary Ansorge

    I wonder which tastes better; a virgin galaxy that has never known the “flesh” of another nebula/galaxy or a well fed cannibal?

    The latter would probably have more “fat”.

    When Andromeda and the Milky Way do their “dance of death”, I wonder if there will be a “big burp” of ionizing radiation, potentially sterilizing most of the life bearing planets in the merged galaxies?

    Gary 7

  3. Kaptain K

    I would disagree that “the time of unrestrained gluttony is in the past”! There are still the Magellenic Clouds out there!

  4. “Obese, gluttonous, and cannibalistic…”
    I thought Phil was talking about me at first. Except for the cannibalistic thing. I’ve never knowingly eaten another human being… um… oh look stars.

  5. Hey, don’t knock cannibalism until you’ve…

    Errr…yeah, look at those pretty stars!

  6. Would someone please hurry up and invent a decent FTL drive? The night skies on planets in there must be *amazing*.

  7. Oli

    “It would make our neighborhood something less than the calm, peaceful place it is now.”

    Because the Milky Way colliding with Andromeda is calm and peaceful?

  8. IVAN3MAN AT LARGE

    A cannibal came home from work to find his wife chopping up some snakes and a very small man. In exasperation, he said: “Oh no… not bloody snake & pygmy pie again!”

  9. Kaptain K

    Obese??
    I’m in shape!
    Round is a shape!

  10. ggremlin

    With something that big I wonder if the blackhole at the center will become too big, reaching some kind of limit and wonderful things happen, best viewed from a distance of course.

    On the other hand, it reminds me of a old commerical:
    “Galaxies, the other white meat!” ;)

  11. That’s quite the Animal House of galaxies you got there! ;)

  12. Jeffersonian

    Insane.

    What would the Milky Way look like in that picture (t0 scale)?

  13. mike burkhart

    Is there anything bad about galaxies absorbing other smaller galaxies ? I mean big fish eat little fish . This happens all the time in nature ,so is it surpriseing it would happen in the universe .

  14. Jon Hanford

    A better view of the gravitational arcs found in 146-IG can be found here: http://www.gemini.edu/images/pio/press_release/pr2010-05/originals/20100506_abell_3827_bw_inverse.jpg

    It turns out that not one but TWO different background galaxies are being lensed by 146-IG!. From the abstract:

    “The most prominent strong lensing feature is a highly-magnified, ring-shaped configuration of four images around the central cD galaxy. GMOS spectroscopic analysis puts this source at z~0.2. Located ~20″ away from the central galaxy is a secondary tangential arc feature which has been identified as a background galaxy with z~0.4.”

    Quite a rare bird. A cD galaxy with multiple nuclei AND two gravitationally lensed background galaxies.

  15. Excellent info as usual Phil!
    There are two other gravitational lens effects in the close up: the faint bluish blobs at the 11 o’clock and 4 o’clock positions. I’ll bet all three are distortions of the same background galaxy; note the two I just mentioned look very similar. Someone should book an HST observation.

  16. Jon Hanford

    (comment awaiting moderation) soooo…..

    It turns out that not one but TWO different background galaxies are being lensed by 146-IG!. From the abstract:

    “The most prominent strong lensing feature is a highly-magnified, ring-shaped configuration of four images around the central cD galaxy. GMOS spectroscopic analysis puts this source at z~0.2. Located ~20″ away from the central galaxy is a secondary tangential arc feature which has been identified as a background galaxy with z~0.4.”

    A better view of the gravitational arcs found in 146-IG can be found here: (http)://www.gemini.edu/images/pio/press_release/pr2010-05/originals/20100506_abell_3827_bw_inverse.jpg

    Quite a rare bird. A cD galaxy with multiple nuclei AND two gravitationally lensed background galaxies. IIRC, time on Hubble is being requested.

  17. Darth Wader

    I think this should be named after my cat: Frito Burrito, Fatty Fatty Boombalaty the Third.

  18. jcm

    Better take antiacids. Let’s just hope it doesn’t turn into a blob, like this:

    source: http://theblob.wikispaces.com/file/view/simp_THOHXVII_Blob_v2f.jpg

  19. Fatty-star Galactica!

  20. Brian

    Why the cannibalism references? Are there not other merger associations that we can make?

    Call the galaxy Goldman-Sachs or J.P. Morgan for causing a wreck and emerging the survivor.

    Perhaps a galactic orgy?

  21. Jess Tauber

    Even if there is an Anthropic Principle explanation for us being here, all these energetic events ‘out there’ mean that we’re still darned lucky not to be where most of the action really is. Not to mention the low-odds formation and continued effect of the moon on our axial orientation, on the tides, etc., a distant Jupiter soaking up errant bodies.

    If spontaneous generation is the rule, the Universe still seems determined to play Whack-a-Mole with life.

    JT

  22. monk

    Galaxy. It’s what’s for dinner.

  23. Chief

    Phil, you said that the core clusters of galaxy’s tend to resist merging together due to their own gravity. Do we assume most cores contain black holes and does this intense gravity mass help in merging, or better yet, overcome a smaller galaxy core to pull mass away to aid the processes.

  24. Jamie

    #20, Cannibalizing is just what astronomers call it

  25. Well judging by the helpful ruler in the picture they are only about 10 inches apart. They should merge into one core in no time at all – Bill

  26. WhiskeyEchoPapa

    Perhaps 146-IG read a pre-publication copy of Olaf Stapledon’s “Nebula Maker” and decided on some extra energy?

  27. Messier Tidy Upper

    Magnificent image & excellent write up there – thanks BA. :-)

    ESO 146-IG 005

    What a “name” – yeesh. Can we rename it the Quintuple Core Cannibal galaxy or the Hannibal Lector galaxy or something better than just that alphanumeric code please?

    @ 20. Brian Says:

    Why the cannibalism references? Are there not other merger associations that we can make.

    Well we do call them galactic mergers and interactions although those terms tend to be used at an earlier stage of the process. The “cannibal” galaxy does consume and absorb (digest?) the smaller “victims” and grow fatter as a result so the metaphor makes good if somewhat gruesome sense. You can use words like engulf, assimilate and co-mingle / inter-mingle and so on if you like but I’m afraid I don’t see the “cannibal” describtion going away anytime soon. The “orgy” analogy would probably seem *more* distasteful to some people (not me but others) and doesn’t make quite as much sense given the partners are indeed permanently devoured rather than being able to depart the room afterwards.

    @ 18. jcm : Eww.. I could’ve done without seeing that frankly .. Gross. ;-)

  28. Pi-needles

    @7. Oli Says:

    “It would make our neighborhood something less than the calm, peaceful place it is now.”
    Because the Milky Way colliding with Andromeda is calm and peaceful?

    Well that’s not happening right *now* – give it a few more billion years then the galactic peace will be broken but right now things are calm.

    @ 19. MichaelL Says:

    Fatty-star Galactica!

    Boom! Boom! LOL. ;-)

    @ 13. mike burkhart Says:

    Is there anything bad about galaxies absorbing other smaller galaxies ?

    Depends which galaxy you are in methinks!

    Seriously, there is the factor that supermassive galaxies like this, probably, aren’t great environments for life – you get lots of high-energy cosmic rays and it’s supermassive black hole core(s?) emit potentially destructive galactic jets* of energy and the spiral disks (ie. where our Sun orbits 2/3rds the way out) are destroyed meaning star – & hence planet – formation probably stops. I don’t think we know for sure but I suspect such galaxies are pretty hostile and sterile cosmic environments.

    Moreover, because they don’t form a lot of new stars and suck up and wreck galaxies that do I think you could argue that, yes, such giant cannibal galaxies are a bad thing esp,. from a perspective of life in the cosmos.

    —–

    * I wonder if this galaxy (or any similar multiple cored cannibal elliptical) could have more than one core galactic jet eg. as seen in M87

  29. Messier Tidy Upper

    @6. David Given Says:

    Would someone please hurry up and invent a decent FTL drive? The night skies on planets in there must be *amazing*.

    Maybe, maybe not.

    It would depend, I imagine, on whereabouts in that Quintuple Cored Cannibal you are located. If you were towards the centre and could see the five cores up close it would perhaps be quite interesting and spectacular – but being an elliptical there would be no band of Milky Way’s disk and bulge and no star forming nebula plus none of the consequent open star clusters. So you’d want to be near the core -which is the least helathy place to be in other ways. :-(

    Most of the stars in this galaxy (esp. the brighter ones) would be old and so you’d get a lot of orange and red giants (incl. long period or Mira variables) but there’d be precious few bright blue-hot O, B & A type young high-mass stars – the odd “blue straggler” excepted. There may be many planetary nebula and almost certainly many times more globular clusters around than in our Milky Way Galaxy but there’d also be a lot of dense star fields – especially if you are in the outer regions – which may block your view of these and of the other incoming “victim” galaxies and the Quintuple Core Cannibal’s own core – or rather cores -themselves.

    So .. hmm .. I’m not so sure. I think our own night sky may in some ways have much richer and better viewing than most of the worlds in that Big Cannibal One. ;-)

    Plus see Pi-needles comment (#29) on why such galaxies – & giant ellipticals generally – are NOT likely to be the most hospitable places for life to form and survie to begin with. :-(

    That said, I would also *love* to have an FTL spacecraft invented A.S.A.P. just so we can get about and explore the wonders in our own Galaxy as well as, yes, seeing others too. :-)

    PS. What type of galaxies is this on the Hubble Sequence (http://en.wikipedia.org/wiki/Hubble_sequence) – anyone know?

  30. Plutonian

    What will happen to that Abell 3827 galaxy cluster in the end?

    Will any galaxies in that cluster escape the central dominant super-cannibal galaxy and survive as separate units or, after a (very long) while, will ESO 146-IG 005 devour absolutely *all* the other galaxies there and *become* the whole cluster all in one humungous elliptical?

    You can easily imagine that any sentient species living in such a one-galaxy-cluster might find it hard to believe in other “island universes” (or ‘galaxies’ as we call them now) existing beyond their own and why they might think their one-whole-galactic-cluster-in-a-single-Galaxy might be the entire universe with nothing existing outside it.

  31. DLC

    It’s not fat, it’s just big boned!

    Mmmm…. smaller galaxy . . . /homersimpson

  32. Jon Hanford

    29. Pi-needles Says:

    “I wonder if this galaxy (or any similar multiple cored cannibal elliptical) could have more than one core galactic jet eg. as seen in M87″

    Galaxies with pairs of jet-like ‘lobes’ have been discovered and are the subject of much attention since they may have been formed by the merger of two supermassive black holes. Try googling “x-shaped radio galaxies” or check out the relevant Wiki page here: http://en.wikipedia.org/wiki/X-shaped_radio_galaxy

    30. Messier Tidy Upper Says:

    “What type of galaxies is this on the Hubble Sequence”?

    ESO 146-IG 005 is classified as cD galaxy, which is from the Yerkes galaxy classification system. These systems can be found near the centers of rich galaxy clusters and are invariably massive, bloated objects. They may contain multiple nuclei or just a solitary nucleus and are fascinating objects to study in their own right (NGC 6166 in Abell 2199 is a bright example of a cD galaxy with multiple nuclei). Again Wikipedia has some great info on these humongous systems: http://en.wikipedia.org/wiki/CD_Galaxy

  33. Sili

    When we’re talking trillions (whether they be échelle longue ou courte) I think using the Sun as the measure has grown useless. We need a bigger standard for comparison.

  34. Albert J. Hoch

    Phil,
    I wish you would pay more attention to your prepositions. “it’s hard to separate out the mass of the galaxy” (Out where?) Is a weaker statement than “it’s hard to separate the mass of the galaxy”, and besides it spoils your steel hard prose!

  35. Messier Tidy Upper

    @34. Jon Hanford : Thanks – I appreciate that answer & those links. :-)

  36. Roby

    The Milky Way is cannibalizing Canis Major Dwarf galaxy right now. It is devouring another one as well, but I forgot the name of the victim.

  37. Lars

    >The Milky Way is considered a big galaxy, and has maybe 400 billion times the mass of the Sun.

    >The mass isn’t exactly clear, but it may be 13 trillion times the mass of the Sun! That’s easily twenty times the mass of the Milky Way!

    Did you write this in a hurry, Phil? Aside from the huge amount of fudge room in the math, converting down to solar masses and then going back up seems more confusing and takes away from the overall observation in the long run. Why not a few simple comparisons?

  38. Judy Yeo

    Nice to know galaxies exhibit all too human traits. how can we be expected to behave better when “nature” is so “untamed”? when all other excuses fail.

  39. lindystar

    Embiggen?……..Embiggened!!? OMG! is that what happened to me?

  40. bigjohn756

    Just call me Abell 3827…

  41. CatMom

    Truly the Garfield of galaxies. Om nom nom!

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