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Surprise! Galaxies Still Evolving in Present Universe

A giant spiral of gas dust and stars, Messier 101 spans 170,000 light-years and contains more than a trillion stars. Astronomers have uncovered a surprising trend in galaxy evolution where galaxies like M101 and the Milky Way Galaxy continued to develop into settled disk galaxies long after previously thought. Credit: NASA/ESA Hubble

Graceful in their turnings, spiral galaxies were thought to have reached their current state billions of years ago. A study of hundreds of galaxies, however, upsets that notion revealing that spiral galaxies, like the Andromeda Galaxy and our own Milky Way, have continued to change.

“Astronomers thought disk galaxies in the nearby universe had settled into their present form by about 8 billion years ago, with little additional development since,” said Susan Kassin, an astronomer at NASA’s Goddard Space Flight Center in Greenbelt, Md., and the study’s lead researcher in a press release. “The trend we’ve observed instead shows the opposite, that galaxies were steadily changing over this time period.”

A study of 544 star-forming galaxies observed by the Earth-based Keck and Hubble Space Telescope shows that disk galaxies like our Milky Way Galaxy unexpectedly reached their current state long after much of the universe’s star formation had ceased. Credit: NASA’s Goddard Space Flight Center

Astronomers used the twin 10-meter earth-bound W.M. Keck Observatory atop Hawaii’s Mauna Kea volcano and NASA’s Hubble Space Telescope to study 544 star-forming galaxies. Farther back in time, galaxies tend to be very different, say astronomers, with random and disorganized motions. Nearer to the present, star-forming galaxies look like well-ordered disk-shaped systems. Rotation in these galaxies trumps other internal, random motions. These galaxies are gradually settling into well-behaved disks with the most massive galaxies always showing higher organization.

This plot shows the fractions of settled disk galaxies in four time spans, each about 3 billion years long. There is a steady shift toward higher percentages of settled galaxies closer to the present time. At any given time, the most massive galaxies are the most settled. More distant and less massive galaxies on average exhibit more disorganized internal motions, with gas moving in multiple directions, and slower rotation speeds. Credit: NASA’s Goddard Space Flight Center

The sampling of galaxies studied, from the Deep Extragalactic Evolutionary Probe 2 (DEEP2) Redshift Survey, ranged between 2 billion and 8 billion light-years from Earth with masses between 0.3 percent to 100 percent that of our own Milky Way Galaxy. Researchers looked at all galaxies in this time range with emission lines bright enough to determine internal motions. Researchers focused on emission lines characteristically emitted by gas within the galaxy. The emission lines not only tell scientists about the elements that make up the galaxies but also red shifting of emission lines contains information on the internal motions and distance.

“Previous studies removed galaxies that did not look like the well-ordered rotating disks now common in the universe today,” said co-author Benjamin Weiner, an astronomer at the University of Arizona in Tucson. “By neglecting them, these studies examined only those rare galaxies in the distant universe that are well-behaved and concluded that galaxies didn’t change.”

In the past 8 billion years, mergers between galaxies, both large and small, has decreased. So has the overall rate of star formation and associated disruptions due to supernovae explosions. Both factors may play a role in the newly found trend, say scientists.

The Milky Way Galaxy may have gone through the same chaotic growing and changing as the galaxies in the DEEP2 sample before settling into its present state at just about the same time the Sun and Earth were forming, say team scientists. By observing the pattern, astronomers can now adjust computer simulations of galaxy evolution until they replicate the observations. Then the hunt will be on to determine the physical processes responsible for the trend.

This cosmological simulation follows the development of a single disk galaxy throughout the life of the Universe; about 13.5 billion years. Red colors show old stars, young stars show as white and bright blue while the distribution of gas shows as a pale blue. The computer-generated view spans about 300,000 light-years. The simulation, running on the Pleiades supercomputer at NASA’s Ames Research Center in Moffett Field, California, took about 1 million CPU hours to complete. Credit: F. Governato and T. Quinn (Univ. of Washington), A. Brooks (Univ. of Wisconsin, Madison), and J. Wadsley (McMaster Univ.).

A paper detailing the findings will be published in the October 20, 2012 The Astrophysical Journal.

Source: NASA


John Williams is owner of TerraZoom, a Colorado-based web development shop specializing in web mapping and online image zooms. He also writes the award-winning blog, StarryCritters, an interactive site devoted to looking at images from NASA's Great Observatories and other sources in a different way. A long-time science writer and space enthusiast, he created award-winning Hubble Star Cards. Use coupon code UNIVERSE to Hold the Universe in your hands. Follow John on Twitter @terrazoom.

Comments on this entry are closed.

  • John Widule October 20, 2012, 1:26 AM

    Galaxies, like all things, were created and perfectly ordered.

    • IVAN3MAN_AT_LARGE October 20, 2012, 2:07 AM

      … by the Flying Spaghetti Monster!

    • Torbjörn Larsson October 20, 2012, 12:21 PM

      That sounds like a creationist speaking, but I will give you the benefit of doubt.

      But as a creationist the comment’s analysis of the presented research says precisely the opposite of what the article describes that everyone can see in nature, to wiz:

      – No structures (here the structure formation central part, galaxies) is created but evolves over time.

      – Nothing was or will be perfectly ordered. The asymptote for heavy galaxies in the 2nd image is quite reasonably never approaching 100 %, because individual galaxies will never conform to absolute absence of disorganized inner motion. Random chance will always let us see some disorganized ones.

      This is of course what we see in the present epoch of cosmology. If we go further back we can see inflation, where universes makes more universes in the simplest physics (which is hard to avoid), or if we go further on we will see dilution, where the structural order of the universe approaches zero again.

      The order history of the universe is zero order to a maximum about now to zero again.

      The order history of the inflationary multiverse is a fractal-like attractor (according to merited physicist Susskind, see his “Fractal-Flows and Time’s Arrow”, arxiv 1203.6440), which looks like chaos on the whole, little if any order on reasonable measures. (I assume there would be a smidgen in a measure of the attractor topological structure.) Here livable universes are the temporary froth on the vast unlivable pond, froth heading into dissolution into the vast pond.

      Quite like the local universe (habitable planets vs universe expansion), except there will always be temporary life somewhere. In that sense we buy life by giving up order, with much of any multiverse order there would likely be no life.

      • bugzzz October 20, 2012, 5:22 PM

        Your post is as interesting as usual T.

        I don’t find an evolving universe and a belief in a higher intelligence (or god, if you like) to be in conflict. There is a contradiction at the heart of creation. Which is true – a universe that birthed itself from nothing, or an intelligence that always existed and designed it? Either answer is absurd, which amuses me. Life is absurd, as would be the absence of life.

        That the universe behaves like a quantum computer suggests many possibilities as to the nature of “god” or whether god is in fact the machine on which the universe runs. It is endlessly fascinating to ponder. For now, lacking proof, it comes down to what you believe.

        • Torbjörn Larsson October 21, 2012, 11:46 AM

          Hm, well, my comment was a bit cryptic due to my hurriedness. But thanks!

          – From a secular viewpoint, religious freedom including the freedom to criticize it, it is easy to see the basic conflict between the two phenomena as they appear to society. Science is in the business to replace belief with facts, and religion is in the business to replace facts with belief.

          You may criticize the claim of “replacement”, but we see this and it is a solid observation. (Say, science replaces the belief in a creator with chemical evolution and cosmology, conversely some religions claim there is a “soul” golem driving our minds so replaces what is observed with what is not). The conflict is thus inherent and unsolvable. And as we all know, science will win because it works while religion never has stated anything factually “true”.

          – From such a viewpoint the agnostic position is really mysterious. How can you not know that science, which today predict the occurrence of the universe and its laws, has support while religion has none?

          Especially the usual religious agnostic that use the theological claim that we can’t know, when we can in principle and we now has evidence predicting that and why there can’t be various forms of magic. I would ask such an agnostic why the rest of us wouldn’t see it as a bit infantile to engage in a “belief in belief”, and on top of that (usually) imply that it isn’t a religiously based idea supported by theological claims when we can all see that it precisely what it is?

          – The generic physics of inflation cosmology seems to be one that a) has no beginning (Susskind) and b) precludes singularities (Vilenkin).

          The latter physics is perhaps incomplete, which makes people suggest that tunneling of universes from various forms of “nothing”, a well known hypothesis and not physically “absurd”, is at hand. There are various forms of stumble blocks for that, and we now have the physics of a) to test, so personally I don’t think b) is very interesting. Plus the idea that inflation is incomplete is based on wishes for deeper theory at the moment AFAIK, we don’t know that it is.

          But if you define nothing as an explicit absence of physics, that becomes absurd. We have physics, and we can’t remove it without dragging non-existent magic into it yet again.

          – Having a creator is indeed absurd, because opposed to a process the infinite ladder of objectified creators and their infinitely increasing “intelligence” (information bound needed for creating the next magiverse) quickly blows up in your face:

          — The ladder predicts nothing generic, since by its own measure it predicts a preceding creator of any initial condition. Absurdity #1.

          — The ladder also doesn’t predict our universe. Why did it stop, and why is the final created object not nothing (if we define it as zero information)? Absurdity #2.

          — Nothing [sic!] motivates using magic. We don’t observe it. Absurdity #3.

          – We know from physics that not only is magic unnecessary for predicting the existence of universes, it is now (with the inflationary standard cosmology, say) so unlikely that it can be rejected.

          • bugzzz October 22, 2012, 3:15 AM

            The thing is though that I’ve been witness to magic in the physical world for 15 years. I’ve detailed some of my experiences here before. What I’m currently pondering is how I might eventually demonstrate or re-create what I’ve experienced in a way that can be measured and observed. This is difficult because it doesn’t really “work that way.” If I showed you something magical, and you observed it with your own eyes in my presence, do you think you would have to rethink your position? The reason I ask is because that is what happened to me. I was an atheist/agnostic and then I had direct physical experiences with the inexplicable. Spirits if you like. Of some form of intelligence not generally or widely perceptible. I was forced to reexamine my beliefs or deny my own senses. And repeatedly for 15 years.

          • IVAN3MAN_AT_LARGE October 22, 2012, 5:02 AM

            Your experience(s) is just anecdotal evidence.

          • Torbjörn Larsson October 22, 2012, 6:32 AM

            That is no “thing” we need to be concerned with here though, since it is anecdote. It could be anything, except actual facts of course because then we wouldn’t have anecdote but observation.

            So to answer your question: no. This is why Randi have a reward for showing the world anything magical, under controlled conditions, with mutually agreed on observations, and with experts on illusions and tricks. And it hasn’t happened, despite ~ 10 billion people having by now a few decades (2?) to do so.

            I admire that in Randi. Instead of accepting people routinely waving around anecdote as if it meant anything at all, except our ability to invent them, he took the societal power out of the field.

          • bugzzz October 22, 2012, 9:37 AM

            You both display disappointing rigidity of thinking. I had actually expected more. Some day soon I may figure out how to show you and the world something undeniable. I am already close. I hope you will not come to regret the limitations you have imposed on yourselves in a universe that is all quantum possibilities.

          • IVAN3MAN_AT_LARGE October 22, 2012, 3:44 PM

            Yeah, good luck with that!

          • bugzzz October 22, 2012, 5:18 PM

            oh, i love a challenge. my entire life has been spent turfing naysayers. i’m adding you to my list for the future. don’t worry, you will hear from me in time.

    • newSteveZodiac October 21, 2012, 8:01 AM

      and potatoes are created perfectly formed by the supermarket. I have seen them with my own eyes and I refute all talk of seed and fields.

    • magnus.nyborg October 21, 2012, 10:16 AM

      Just like the banana.

  • wavettore October 20, 2012, 2:43 AM

    New and old Science
    A new and Progressive Science shows how Wavevolution, or the transformation from waves to atoms, is the connecting link that closes the circle of science to open new horizons never seen before.
    The bureaucracy of traditional science prevents the recognition of any event unless certain criteria are first met. The problem of this science is buried deep right in the compilation of these “laws” or criteria introduced by a few scientists in the name of all science and from their erroneous understanding of the relation between Space and Time. This antiquated system of rules also results in misleading theories.
    For example, the Space is not “curved”.
    In Einstein’s paradigm, a stone that falls on the ground from the window of a moving train also marks one parabola in Space. Although, this path is only apparent since also the Earth is moving and the Time spent by the stone to reach the ground has also changed to some degree that imaginary vertical line. At the Time of the initial Movement when the stone falls from the window it exists only one perpendicular Space which is not anymore the same as the stone continues to move until it hits the ground. If the scientist had known that the coordinates of Space in Time are unique and unrepeatable then all the rest would have also been “straight”. That perpendicular is straight but accounted as “curve” because of the limits of science unable to recognize the issue of simultaneity. In reference to any body on each moment in Time there are always only two coordinates in Space.
    And with two coordinates there is no curve.
    The perpendicular changes in Time but Einstein believed that the concept of Space is independent from the concept of Time.
    Another example is in the special theory of relativity which denies all absolutes and meanings of truth. This is in regard to Einstein’s example of two beams of light hitting one same embankment of a railroad on two Points: Point A and Point B. In between the two there is also the middle point, Point M. If one train was running over that track then on the train we would also have Point A1 on the wagon of the train correspondent to above Point A and also one other corresponding Point B1 right above Point B. We would also have on the train the corresponding Point M1 above Point M. Einstein’s theory is that as for Point M (not moving because on the embankment) those two beams are simultaneous and equidistant instead for the passenger sitting on M1 and moving towards Point B1 (and also toward Point B) the two beams are not simultaneous because the beam in Point B1 is being approached by the moving train, therefore closer to M1. In this example, while Einstein’s concept of Time is rigidly kept unchanged in regard to the embankment instead the concept of Space is extended to also the next moment in Time when the traveler will move even if in that precise instant the traveler has not moved yet. Since the concept of simultaneity had been put aside, Einstein considered Time to be the same while Space instead had changed.
    Also, this same scientist erroneously believed that all colors in the light spectrum travel at the same speed.
    Much confusion comes from these approximations.
    One new Awareness will be found in between the winding creativity of the human mind and the rigid logic of numbers.



  • IVAN3MAN_AT_LARGE October 20, 2012, 2:45 AM

    Here’s the link to the relevant paper: The Epoch of Disk Settling: z~1 to Now.

  • Steve Nerlich October 20, 2012, 11:36 AM

    Surely it’s all about density waves. It must take a while for mean forces to become established – but when they do, you get the characteristic spiral galaxies that we see frequently and nearby in the contemporary universe,

  • lcrowell October 21, 2012, 1:06 PM

    The evolution of galaxies by this accreting process of smaller structures appears to have some sort of attractor basin. A basin of attraction is a set of final states that in the case of an attractor point means there is only one final state. For complex systems, or systems that have a driving potential or force along with an attenuating system that dissipates energy the basin of attraction can define a set of orbits. The spiral galaxy appears to reflect this basin of attraction.
    We are all familiar with Newton’s law of gravity. For two masses M and m at a distance d apart their mutual attractive force of gravitation has magnitude F = GMm/d^2, for G the Newton constant of gravity. The force between all the stars in a complex structure is a summation over all these forces. A great sum over all the forces on each star then results from Newton’s second law of motion F = ma, which is a differential equation of motion for each star.
    We have to include the contribution from dark matter, which is four times the contribution of ordinary matter. This stuff exists in a halo that encompasses the galaxy. Hence the total mass of dark matter is M = ? times volume, for ? the density of dark matter, or in greater generality ??dV, as an integration. The acceleration of gravity on a sphere that of surface area S that surrounds the dark matter halo is then integrated as
    ?a•ds = ??•a dV
    where V is the volume inside the sphere that bounds the dark matter. This equation is Stokes’ rule. For simplicity we let ?a•ds = 4?R^2 a, for R the radius of the dark matter sphere. The acceleration evaluated at the boundary is a = [?(4?/3)R^3]/R^2 = ?(4?/3) ?R. Thus
    ?a•ds = 4?R^2 a = (4?)^2/3 G?R^3
    The right hand side we simplify this as ??•a dV = ?•a (4?/3)R^3. Putting this together we have
    ?•a = 4?G?.
    This is often written with the gravity potential ? with a = ??, as
    ?^2? = 4?G?,
    which is the Poisson equation — a very basic equation learned in undergraduate level physics. It is easy to find the acceleration which is
    a = G?r/3.
    This is then added to the above computed acceleration of each star. This is the force of a spring, or the harmonic oscillator. The radius r is computed from the center of this matter distribution.
    We then have some attenuating force due to gas and dust clouds that collide with each other. This is a part of setting up density waves. The elliptical orbits that are deviate from Kepler’s laws are due to dark matter and the spring force on each star. This attenuating force or friction will be of the form f = -?v, for v the velocity of each galaxy and ?a constant that is estimated by observations. We now put all of this together. Acceleration is a = d^2r/dt^2 and velocity is v = dr/dt and so the motion of each star is given by
    d^2r/dt^2 = sum_i Gm_i/|r – r_i|^2 + G?r/3 –?dr/dt
    for the sum over all other stars with mass m_i at positions r_i. So everything seems in order (though I have rather shamelessly glossed over some details), but solving this equation would be horrendously difficult — in fact it is impossible.
    So in this age of computer we do a finite element procedure. The velocity in a finite element setting is
    dr/dt = r(t_{i+1}) – r(t_i)/(t_{i+1 – t_i)
    and you can show the acceleration is
    d^2r/dt^2 = r(t_{i+1}) – 2r(t_i) + r(t_{i-1})/(t_{i+1 – t_i)^2.
    Now write a finite element computer program to solve r(t_{i+1}) according to r(t_i) and r(t_{i-1}), from previous iterations, update after computing by setting r(t_i) to r(t_{i-1}) and r(t_{i+1}) to r(t_i) (in that order!) and you let the computer crank away on it.

  • Mike October 21, 2012, 10:43 PM

    It is like the Universe is really alive.

    • bugzzz October 22, 2012, 3:18 AM

      Some believe the universe is filled with intelligence. I’m among them.

      • SJStar October 22, 2012, 6:37 AM

        That ain’t science and not how it works. Science isn’t “best guess.”

        • Dunc Grootjen October 24, 2012, 5:06 PM

          If you do not believe, you will never figure out wether your beliefs are true or not.Science can be done in 2 ways… by accident and by believing.

  • Prism2Spectrum October 23, 2012, 1:16 PM

    “Both religion and natural science require a belief in God for their activities, to the former He is the starting point, and to the latter the goal of every thought process. To the former He is the foundation, to the latter, the crown of the edifice of every generalized world view.” — Max Planck, German theoretical physicist who originated quantum theory, which won him the Nobel Prize in Physics in 1918

    “Lecture, ‘Religion and Natural Science’ (1937) In Max Planck and Frank Gaynor (trans.), Scientific Autobiography and Other Papers (1949), 184.” ______________________________________________________________

    ~ Could it just be, the basic foundation of all knowledge, from which all Scientific constructs can be firmly based, and built-up, lies in one Book of revealed knowledge? If allowed to, time will tell its beginning story: How did the Universe come to be? Why does life breath? What is the final end of it all, for us to understand and see?

    Well, one highly detailed version is here given. How much of that rests on hypotheses, accepted as reality, theories, taken as intrinsic truths, I cannot say. But I see enough to be amazed, at how there are those who assert things—unproven—as if there are as true as the orbiting Moon of Earth’s night. Highly educated men, intellectually gifted, who could run multiple ringlets of details around me, personally, before I could say “what”.

    Will the final answer(s) come to rest on one basic knowledge-set, one foundation support (a sort of “grand unified field theory”, if you will) that has been resting on bookshelves for centuries? Time will tell, if open minds allow her to speak her marvelous secret things from the Earth’s inner microcosm, invisible, and the heavens outer macrocosm, inscrutable.

    Could it be, is it possible that, one Foundation could actually support the crowning Entablature presently being cast from all true Science, held-up by its various pillars? Majestic pillars which rise from the Earth of man to the heavens of …? The frontiers of Science, on both ends (beneath the land, and above the sky), seem to be reaching towards, or have actually reached the edge of, our perceptible, material reality, and are peering into, glimpsing perplexing reflections of an alternate—fare greater Reality:

    A bubble bath of Murltiverses, endlessly foaming-out new cosmic variations? Or, Something else?

    (Note: I am simply contributing my late-arriving two cents to an interchange of discussion.)

  • katesisco October 23, 2012, 10:36 PM

    Great science. I have this idea that if the galaxies are moving toward a ‘standardized form’ then they can hardly be this ‘starless dark’ noted here: p://idealab.talkingpointsmemo.com/2012/07/dark-starless-galaxies-observed-for-the-first-time.php
    This article at idealab.talkingpointsmeno.com says the ‘starless dark’ is working toward becoming spirals. I wonder if that is just the opposite; that spirals form globular clusters when new and almost immediately degrade and lose their magnetic field and blow out energy through the galactic equator to the rim where new blue stars form. This off gases tremendous amounts and the gas eventually envelops the entire galaxy. The outside of the gas shell cools and Viola! you have a ‘starless dark.’

    The timeline would then be: tight spirals form globular clusters axially, relax and exhaust energy through the galactic equator to the rim forming new stars only when and if there is an unblance in the mass of the galaxy to the center nucleus(the tao), and eventually stop producing energy cum stars as the enveloping gas clouds from star creation cocoons the galaxy in a gas shell which from the outside is cold and hence appears as a ‘starless dark.’