Eight-Billion Year View of Galaxy Evolution (VIDEO)

 

 

          

 

A comprehensive study of hundreds of galaxies observed by the Keck telescopes in Hawaii and NASA's Hubble Space Telescope has revealed an unexpected pattern of change that extends back 8 billion years, or more than half the age of the universe.

"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. "The trend we've observed instead shows the opposite, that galaxies were steadily changing over this time period."

Today, star-forming galaxies take the form of orderly disk-shaped systems, such as the Andromeda Galaxy or the Milky Way, where rotation dominates over other internal motions. The most distant blue galaxies in the study tend to be very different, exhibiting disorganized motions in multiple directions. There is a steady shift toward greater organization to the present time as the disorganized motions dissipate and rotation speeds increase. These galaxies are gradually settling into well-behaved disks.

The plot below 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.

 

         

Blue galaxies -- their color indicates stars are forming within them -- show less disorganized motions and ever-faster rotation speeds the closer they are observed to the present. This trend holds true for galaxies of all masses, but the most massive systems always show the highest level of organization.

Researchers say the distant blue galaxies they studied are gradually transforming into rotating disk galaxies like our own Milky Way.* "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."

Rather than limit their sample to certain galaxy types, the researchers instead looked at all galaxies with emission lines bright enough to be used for determining internal motions. Emission lines are the discrete wavelengths of radiation characteristically emitted by the gas within a galaxy. They are revealed when a galaxy's light is separated into its component colors. These emission lines also carry information about the galaxy's internal motions and distance.

The team studied a sample of 544 blue galaxies from the Deep Extragalactic Evolutionary Probe 2 (DEEP2) Redshift Survey, a project that employs Hubble and the twin 10-meter telescopes at the W. M. Keck Observatory in Hawaii. Located between 2 billion and 8 billion light-years away, the galaxies have stellar masses ranging from about 0.3 percent to 100 percent of the mass of our home galaxy.

The Milky Way galaxy must have gone through the same rough-and-tumble evolution as the galaxies in the DEEP2 sample, and gradually settled into its present state as the sun and solar system were being formed.

In the past 8 billion years, the number of mergers between galaxies large and small has decreased sharply. So has the overall rate of star formation and disruptions of supernova explosions associated with star formation. Scientists speculate these factors may play a role in creating the evolutionary trend they observe.

Now that astronomers see this pattern, they can adjust computer simulations of galaxy evolution until these models are able to replicate the observed trend. This will guide scientists to the physical processes most responsible for it.

The DEEP2 survey is led by Lick Observatory at the University of California at Santa Cruz in collaboration with the University of California at Berkeley, the University of Hawaii at Manoa, Johns Hopkins University in Baltimore, Md., the University of Chicago and the California Institute of Technology in Pasadena.'

 

            

A paper describing these findings will be published Oct. 20 in The Astrophysical Journal.

Comments

[wavettore]

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 our eyes toward 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 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, 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 the Earth is also 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 its potential trajectory is one perpendicular Space that is no longer 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 each body on each moment in Time there are always only two coordinates in Space for one perpendicular.
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 were to run 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 also to 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.

http://www.wikinfo.org/Multilingual/index.php/Wavevolution

[paper man]

tl;dr