Tuesday, July 23, 2013

Why does the universe have fewer dwarf galaxies which should?

Turn and shoot the Question: "What about the sun?". "He went to sleep," his mother answered thinking an explanation that satisfies the curiosity of his three years. "He night," says halfway between the statement and the question and question again looking at the sky: "What about the moon? In these sentences, little seems to sum up, with its childlike simplicity-the concerns, from primitive man to the present day, led mankind to observe the sky for answers to many questions.

That search continues and becomes increasingly complex features, as astronomers are finding some explanations. One of the current problems trying to resolve the Astronomy and carrying more than a decade without a solution is that the theoretical models predict the existence of thousands of dwarf galaxies in the universe, but astronomical observations only displayed a few dozen. This contradiction was established in 1999 as the "problem of missing galaxies".

Alejandro Benitez-Llambay and Mario Abadi, scientists at the Institute of Theoretical and Experimental Astronomy (UNC-CONICET) and the Astronomical Observatory of Cordoba (UNC), both in Argentina, together with colleagues from Germany, Israel, Canada and Spain, proposed an innovative explanation.

In short, astronomers propose that during development, these dwarf galaxies densely crossed dust and gas in the universe, in that process lost the gas needed to form stars, and that stopped growing. How lost their gas? "For the friction that occurs between two gaseous media that move through each other", explains Benítez-Llambay.

By definition, galaxies have a thousand million stars. The "dwarf", however, have just ten to a hundred billion stars in its interior. The Argentine scientists work focused on the latter, particularly those which are scattered in the universe without gravitational relationship with the Milky Way.

The study involved making a virtual universe. In a supercomputer located in Spain, we simulated the evolution of a sector of the universe, from the Big Bang to the present, something like 13,700 million years. The software should solve the equations worked several months. The idea was to "compress" the life of the universe and could look under the animation format.

This enabled them to observe that although the universe emerged from a starting point where the distribution of matter was homogeneous, eventually began to show small irregularities or "lumps" where the gravitational force (attraction) was greater than the expansion. These singularities were isolating themselves and becoming denser. Thus were formed the stars and then galaxies.

The fact is that galaxies were formed in a privileged region of high density. Some of them, isolated and still in embryonic stages, crossed the area of ​​high concentration of dust and gas, and "friction generated wind tunnel blew them all the gas," explains Mario Abadi.

"If you look in detail (simulated) are galaxies and a kind of tails, like comets. They left a trail. They passed through this area of ​​high density and all its equipment was stolen. Longer term, the consequence is that these galaxies were stripped of all the gas, the fuel needed to create stars. Failed to form the stars and was what I call 'galaxies frustrates' because they never become such, "he adds.

This would explain why theoretically expected the existence of a number of galaxies and are really only a few.

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