New theory says galaxies formed due to intensive cosmic streams of cold gas

January 22nd, 2009 - 2:37 pm ICT by ANI  

Washington, Jan 22 (ANI): Cosmologists at the Hebrew University of Jerusalem have come up with a new theory as to how galaxies were formed in the Universe billions of years ago, attributing their formation to intensive cosmic streams of cold gas, and not galactic mergers.

The new theory has been put forward by a cosmology research group, led by Professor Avishai Dekel, who holds the Andre Aisenstadt Chair of Theoretical Physics at the Racah Institute of Physics of the Hebrew University.

The hypothesis takes issue with the prevailing view on how the galaxies came to exist.

The new theory, motivated by advanced astronomical observations and based on state-of-the-art computer simulations, maintains that the galaxies primarily formed as a result of intensive cosmic streams of cold gas (mostly hydrogen) and not, as current theory contends, due primarily to galactic mergers.

The researchers show that these mergers had only limited influence on the cosmological makeup of the universe as we know it.

The galaxies are the building blocks of the Universe. Each of them comprises some hundred billion radiant stars, such as our sun, which extend across about 50,000 light years.

Every galaxy is embedded in a spherical halo made of dark matter that cannot be seen but is detected through its massive gravitational attraction. The exact nature of this matter is still unknown.

The galaxies are composed into two major types: spiral and elliptical. The spiral galaxies, such as our Milky Way, are rotating disks, rich in hydrogen gas, and are constantly forming new stars.

The attempt to understand the way in which these two types of galaxies form is the primarily challenge facing modern cosmological researchers.

The question that emerged was how these galaxies were able to form stars so quickly and in large quantities at such an early stage without massive galactic mergers.

Professor Dekel and his Hebrew University and French associates, pose their new theoretical model, which explains these observed phenomena.

Their findings are based on computer simulations carried out by the French researchers headed by Professor Romain Teyssier.

The simulations, using one of the most powerful supercomputers in Europe, made it possible in an unprecedented manner to carry out a detailed investigation of how galaxies formed in the early Universe.

The picture that emerges is of galaxy-building that results from a continuous flow of cold gas along a few narrow streams rather than by mergers. (ANI)

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