Dark Energy Model Explains 'Hubble Sequence' of Galaxies
Written by Nancy Atkinson
Caption: A figure illustrating the Hubble sequence. Image: Ville Koistinen
One look at a Hubble Deep Field image reveals that galaxies come in all sorts of shapes and sizes. But why? Astronomers have been at a loss to explain the diversity of galaxy shapes seen in the Universe. But now, two astronomers have tracked the evolution of galaxies over thirteen billion years from the early Universe to the present day, helping to clarify the "Hubble Sequence," a classification of galaxies developed by Edwin Hubble. Keys to their model include galaxy mergers and dark energy.
Dr. Andrew Benson of Caltech and Dr. Nick Devereux of Embry-Riddle University in Arizona Benson and Devereux combined data from the infrared Two Micron All Sky Survey (2MASS) with sophisticated computer model they developed, called GALFORM. The model reproduced the evolutionary history of the Universe over thirteen billion years. To their surprise, their computations reproduced not only the different galaxy shapes but also their relative numbers.
Caption: The image shows some of the galaxies generated by the computer model. The yellow objects are most distant and therefore appear as they were 13 billion years ago, whilst those closer are seen as they looked more recently. Image: A. Benson (University of Durham), NASA / STScI
“We were completely astonished that our model predicted both the abundance and diversity of galaxy types so precisely,” said Devereux. “It really boosts my confidence in the model,” Benson said.
The astronomers’ model is underpinned by and endorses the ‘Lambda Cold Dark Matter’ model of the Universe. Here ‘Lambda’ is the mysterious ‘dark energy’ component believed to make up about 72% of the cosmos, with cold dark matter making up another 23%. Just 4% of the Universe consists of the familiar visible or ‘baryonic’ matter that makes up the stars and planets of which galaxies are comprised.
Galaxies are thought to be embedded in very large haloes of dark matter and Benson and Devereux believe these to be crucial to their evolution. Their model suggests that the number of mergers between these haloes and their galaxies drives the final outcome – elliptical galaxies result from multiple mergers whereas disk galaxies have seen none at all. Our Milky Way galaxy’s barred spiral shape suggests it has seen a complex evolutionary history, with only a few minor collisions and at least one episode where the inner disk collapsed to form the large central bar.
In Hubble's classification, there are three basic shapes: spiral, where arms of material wind out in a disk from a small central bulge; barred spiral, where the arms wind out in a disk from a larger bar of material; and elliptical, where the galaxy’s stars are distributed more evenly in a bulge without arms or disk. The different types clearly result from different evolutionary paths, which Benson and Devereux's model now explains.
“These new findings set a clear direction for future research. Our goal now is to compare the model predictions with observations of more distant galaxies seen in images obtained with the Hubble and those of the soon to be launched James Webb Space Telescope (JWST)”, said Devereux.
Their results appear in the journal Monthly Notices of the Royal Astronomical Society.
Benson and Devereux's paper.
Lead image complete caption: A figure illustrating the Hubble sequence. On the left are elliptical galaxies, with their shapes ranging from spherical (E0) to elongated (E7). Type S0 is intermediate between elliptical and spiral galaxies. The upper right line of objects stretch from Sa (tightly wound spiral) to Sc (loosely wound spiral). The lower right line shows the barred spirals that range from the tightly wound SBa to loosely wound SBc types. Image: Ville Koistinen
Source: RAS
Filed under: galaxies
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January 13th, 2010 at 3:49 am
Interesting; so we can model the universe but not quite understand it.
The uncertainty principle at play. We can look and not understand but understand by not looking.
On an aside: I think its awesome that we travel in space without leaving the earth. Between our telescopes, observation and the models we create we are already voyagers in the data that is the universe.
Sure, it could be better if we could also go there in person, but this is not bad at all in the interim.
Damian
January 13th, 2010 at 5:43 am
Distribution of dark matter and dark energy in space is really an attractive challenge and such type of modelling will help to enhance our knowledge and ideas about universe.
Lalit from HP INDIA
January 13th, 2010 at 6:39 am
I'm still thinking that the dark matter structures may have formed first, and the galaxy building blocks were attracted to them.
January 13th, 2010 at 6:57 am
I downloaded the paper, but have not yet read this for detail. This is complicated stuff. I have a question. The spiral shape is thought to be due to density waves. Does dark matter play a role in density waves?
LC
January 13th, 2010 at 10:35 am
LBC, very likely since dark matter does influence through gravity and the disk orbiting suggested something very weird happening since the orbits do not follow the inverse square law at the disk shape.
The question his how strong does it influence it?
January 13th, 2010 at 11:02 am
And of course early galaxies are irregular before becoming spiraly, as noted in a posta few days ago.
Interesting that Hubble got it right (system evolution), though his sequence is convoluted the wrong way.
@ damian:
I would put it as we can model, or do science in general, without having a complete model at once.
January 13th, 2010 at 2:58 pm
Now that's a nice little result for them!
January 13th, 2010 at 6:27 pm
From the post: " Here ‘Lambda’ is the mysterious ‘dark energy’ component believed to make up about 72% of the cosmos, with cold dark matter making up another 23%. Just 4% of the Universe consists of the familiar visible or ‘baryonic’ matter that makes up the stars and planets of which galaxies are comprised."
Let's see: 72% 'dark energy", 23% 'dark matter".
And these figures vary depending on the report you read.
So, 95% of the energy and matter can't be detected and never has been detected and they can make a simulation???
Where they know where ALL the matter and energy resides and how it reacts???
At least over at Space.com they had commenters challenge this preposterous clain. Many noting "dark matter" has never been detected.
Here, at Universe Today everybody accepts it without a thought.
What a sterile intellectual environment.
January 13th, 2010 at 8:19 pm
..and a least 100% of us know what the jackass Anaconda says is simply and totally ridiculous!!
January 13th, 2010 at 8:45 pm
Clearly dark matter exists by various arguments. The disklike rotation of galaxies indicates the material we see is immersed in a mass distribution. Further, the Einstein lensing of more distant galaxies gies a mass value larger than expected from just luminous gas and stars we see. What I find interesting is what role this serves in the structure of galaxies.
LC
January 13th, 2010 at 10:04 pm
Those interested might find the following link of the certified madman A.Peratt's quite insane and rejected galaxy formation theories; I.e. Mystery Behind Galaxy Shapes Solved
Now we know why EU is considered such absolute drivel. The biggest mystery remains is why these jackasses think they are right!
January 14th, 2010 at 5:05 am
This stuff is balderdash guarded by various conspiratorial ideology.
LC
January 14th, 2010 at 12:34 pm
An explanation that doesn’t rely on “a massive black hole”, consider this:
3 – Dimentional Particle-In-Cell Simulations of Spiral Galaxies
A. L. Peratt, W. Peter, and C. M. Snell
Los Alamos National Laboratory
1990 International Astronomical Union – Provided by the NASA Astrophysical Data System
http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1990IAUS..140..143P&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf
“Abstract: …fully relatavistic particle simulations allow a detailed study of a magnetized plasma galaxy model…Simulation derived morphologies, radiation intensities, frequency spectra and isophote patterns are produced by the model which can be directly compared to observational data…of barred spiral galaxies…”
Hold both models (this one and the black hole model) in the back of your mind and as more data is produced from observation & measurement, see which model does a better job of explaining the observations & measurements.
Plasmoid: Plasma-Magnetic-Enity
Ah, the hostility — yes, that's the reaction of people confident in their beliefs.
Certainly, the reaction of people that are interested exploring ideas and observations & measurements.
January 14th, 2010 at 12:40 pm
Oh, and I almost forgot: Doesn't rely on so-called "dark energy" and "dark matter".
Why? Because the rotational curves work out, the edge of galaxies move at the same speed as the core, which after all is how "dark matter" was invented.
But for the failure of the gravity "only" model to account for the rotational curves problem, "dark matter" would have never been thought of.
Sorry, boys and girls, your model was falsified and you were too dogmatic to accept its failure so you made stuff up.
You folks can convince yourself, all right, but nobody else who knows the story buys the "stuff".
January 14th, 2010 at 2:37 pm
We now have supercomputers that make the computer used in that 1990(!) simulation look like a bloody abacus!
Nobody here "buys the 'stuff'" because it's available for free; actually, it's only EU/PC proponents who do the actual buying by purchasing books written by Dr(!) Anthony L. Paratt, et al., on outdated pseudoscience rubbish!
January 14th, 2010 at 4:39 pm
@Anaconda
"Ah, the hostility — yes, that's the reaction of people confident in their beliefs."
Least we believe in observation and relevant theory. All you do is follow you do is follow unproven or rejected nonsense.
Anyone worshiping someone like Anthony L. Pratt is really is deluding themselves,
Wouldn't expect anything different from a jackass, eh Anaconda?
January 14th, 2010 at 4:49 pm
Anaconda's desperate attempts in trying to engage individuals here is an illusion, and is certainly not genuine. From his history in expressing irrelevant alternative comments and stating his "personal theories" here, it is clear all he wants to do is spread hearsay instead of discussing the issues presented in the news story at hand.?Towards any here, the individual known Anaconda has been pointed out by the writers here as a TROLL, and have suggested we just ignore him – and perhaps he'll have the sense to go away for good.?There is no need to "prove him wrong" or even correct in his views, In the end this treatment he has brought on himself.
IMO, the only way he can redeem himself is through improving his own behaviour, instead of trying to corrupt others or highjack the discussion to his own ends. Until he discuss the issues in a rational and logical manner, he should be ignored or discussed in the third person.Engaging him only encourages his poor behaviour, and unless responders are willing to ignore this individual, we will only perpetuate the same old rhetorical nonsense.
There is a great saying. "'For things to change, i must change." And this importantly applies to this individual.
I'd suggest he should be encouraged to do so.
Until then, I recommend we just ignore him – for all our sakes.
Thanks
January 14th, 2010 at 5:15 pm
Crumb:
Your best bet is to read the paper.
Learn some plasma physics, it won't bite you
January 14th, 2010 at 5:42 pm
Actually, your best bet is to print out the mentioned article onto (recycled) paper and use it as toilet paper!
January 14th, 2010 at 7:03 pm
Ivan3Man:
Impressive, one of your more intellectual comments
January 14th, 2010 at 7:11 pm
Anaconda's desperate attempts in trying to engage individuals is to perpetuate an illusion, whose response is certainly not genuine. From his long history here he just continues to express many irrelevant alternative comments often stating his own "personal theories." It is very clear all he wants to do is spread hearsay instead of discussing the issues presented in the news story at hand.
?Towards any newer readers here who don't know, this individual known "Anaconda" has been pointed out by the contributors here as a TROLL,
It is commonly suggested we just ignore him – and perhaps he'll have the sense to go away for good.? There is absolutely no need to "prove him wrong" or even correct his unfounded views, In the end this drastic treatment he has brought on himself.
IMO, the only way he can properly redeem himself is through improving his own behaviour, instead of trying to corrupt others or highjack the discussion to his own ends. Until he discuss the issues in a rational and logical manner, he should be ignored or discussed in the third person.Engaging him will only encourage his rather poor behaviour, and unless responders are willing to ignore this individual, we will only continue to perpetuate the same old rhetorical nonsense.
There is a great saying. "'For things to change, I must change." And this importantly applies to this very misguided individual.
I would suggest he should be encouraged to do so.
Until then, I recommend we just ignore him – if only for all our sakes.
Thanks.
January 15th, 2010 at 5:45 am
So, what was THIS topic about?
January 15th, 2010 at 11:17 am
DrFlimmer:
This topic is about a computer simulation where the data input was "tailored" to get results that match observation & measurement.
How so, you might ask?
It is evident because Science doesn't know what "dark matter" or "dark energy" is or if it even exists or what its physical properties are beyond "dark matter" has gravitational attraction or "dark energy" has physical repulsion.
Nothing about these substances are quantified. If they aren't quantified then what is being fed into the computer?
It's obvious this is a case of reverse engineering. Look at the galaxy and then determine what inputs into the computer program will generate the desired results.
Theorists don't even know where this "stuff" resides in relation to galaxies.
What is assumed is no better than speculation.
Put those two properties together and it sounds like electro-magnetic properties — which has BOTH physical attactive and repulsive properties.
But why make "stuff" up when Science knows electro-magnetic plasma has both properties.
The paper linked by myself runs a computer simulation considering physical properties that are KNOWN and quantified in advance and result in data that matches known properties of double lobe radio galaxies.
The properties of magnetized plasma are known by experimental results in plasma physics laboratories and in situ satellite probes in space plasma. Its properties have been quantified by laboratory and in situ observation & measurement.
Nothing like that can be said for "dark matter" or "dark energy".
By the way, how do you falsify "dark" matter?
January 15th, 2010 at 12:57 pm
ACHTUNG COMMENTERS!
January 16th, 2010 at 4:09 pm
Anaconda said;
"By the way, how do you falsify "dark" matter?"
Easy. Just listen to the bull&%#$ said by yourself!
January 18th, 2010 at 12:35 pm
"it's just a model."
No need to get so upset…
January 24th, 2010 at 2:01 pm
Here's an interesting factoid about the Peratt simulations: they do not include stars.
Here's an interesting factoid about galaxies: they contain lots of stars.
The source code for the Peratt simulations has been published, along with his own ideas on how it can be extended to make them more realistic … yet no one seems to have bothered to pick up the baton – in over 20 years! – despite the fact that it should be quite straight-forward, require no more than an ordinary desktop PC, etc.
Curious, n'est pas?