Astronomers have discovered why galaxies have different forms
In 1926, the famous astronomer Edwin Hubble developed morphological classification of galaxies. This method divided the galaxy into three basic groups - elliptical, spiral and lenticular. Since then, astronomers have devoted a significant amount of time and effort to figure out how galaxies evolve over billions of years and why they acquire precisely those forms that will eventually acquire.
One of the most popular and widespread of hypotheses on this score is the one that explains the change of galaxies forms the result of the merger, when a compact star clusters, held mutual gravity, merge and thus eventually form the shape and the final form of galaxies. However, according to the findings of a new study conducted by an international group of scientists, the shape and size of the galaxies may in fact influence the emergence of new stars in their central areas.
The study was conducted under the leadership of Ken-Ichi postdoctoral Tadaki in collaboration with the Institute for Extraterrestrial Physics and Max Planck National Astronomical Observatory of Japan (NAOJ). To obtain a more complete picture of galactic metamorphosis scientists conducted a series of observations of very distant galaxies.
Chart of the evolution of galaxies The study included the use of multiple telescopes, through which astronomers have observed 25 galaxies, located at a distance of about 11 billion light-years from Earth. At this distance, scientists have actually conducted surveillance of galaxies as they looked exactly 11 billion years ago, that is, after about 3 billion years after the Big Bang. This time is considered as a period astronomers activity peak galactic formation in the universe, formed when most of the galaxies.
"I think that massive elliptical galaxies were formed by collisions of galactic disks. However, we are not sure that all elliptical galaxies once affected this intergalactic event. We believe that there is an alternative, "- said Tadaki in a press release published on the website of the Japanese astronomical observatory.
The ability to catch a faint light of distant galaxies proved to be very challenging, and to solve it, the scientists needed to use two terrestrial and one space telescopes. First, to find 25 galaxies they used the 8, 2-meter Subaru telescope located in Hawaii. Then observed the detected objects with the Hubble Space Telescope and ground Atacama large array millimeter wave (ALMA), situated in Chile. Hubble has allowed to catch the light of galaxies to determine their shape (they had 11 billion years ago), using ALMA researchers conducted a study of submillimeter waves emitted by cold dust clouds and gas, a place where new stars are born. Comparing the results of both the observations, the astronomers were able to identify a detailed picture of how the galaxy looked 11 billion years ago, when their form is still subject to change.
Observation of the galaxy, located 11 billion light-years away
The fact that scientists have found, turned out to be very revealing. Image "Hubble" pointed out that in early galaxies dominated disc component, rather than central bar, which we used to associate with spiral and lenticular galaxies. At the same time ALMA images showed that close to the center of these galaxies can be massive tanks of gas or dust, within which there is a very active star.
To exclude the possibility that such active star formation could be caused by the merger of galaxies, the researchers also used to verify the data from the Very Large Telescope of the European Southern Observatory, located at the Paranal Observatory in Chile.
"Here we have conclusive evidence that the dense galactic nuclei can be formed without galactic collisions. They can be formed due to a very active star formation in the heart of the galaxy, "- said Tadaki.
The results of this research could make astronomers rethink current models and theories of galactic evolution, as well as some aspects such as how galaxies appear bridges and spiral arms. The research may also lead to a revision of cosmological models of evolution, not to mention the history of our own galaxy.
Who knows, maybe it will also force astronomers to revise the predictions about what may happen when our Milky Way galaxy and Andromeda collide in a few billion years. The more and deeper scientists are looking into space, the more surprises it presents. And each time, when there was no observations were consistent with our expectations, it forces scientists to reconsider the hypotheses concerning the evolution of the universe.