Cosmic vibrations reduce the mass of galaxies

The new study, published July 30 in Nature, explains the origin of spherical dwarf galaxies.

The globular dwarf galaxies are very small and very fuzzy, the total star weight of which is very small compared to the weight of the whole galaxy. They are formed primarily from dark matter - the mysterious material that can only be identify through gravity effects.In the universe, the mass of dark matter is five times the mass of ordinary matter.

Astronomers have discovered that it is difficult to explain the origin of spherical dwarf galaxies. Previous theories required these galaxies to move around nearby large galaxies, such as the Milky Way, for example, but this did not explain the dwarfs that appeared outside the Local Galaxy group. ( "Local Group" ) has been formed.

'These are dwarf galaxies in the early universe, and one of the main goals of modern cosmology is to understand how they form,' said Elena D'Onghia, team leader, staff. Harvard-Smithsonian Center for Astrophysics (CfA), said.

D'Onghia and her colleagues used computer models to test two hypotheses about the formation of spherical dwarf galaxies: 1) two dwarf galaxies far from large galaxies like the Milky Way and touch each other, and one of the two galaxies later merges into the Milky Way; 2) a dwarf galaxy colliding with the Milky Way is forming in the early universe.

This model illustrates the process of star separation due to the effect of gravity resonance. Stars of dwarf galaxies (below the picture) move around a larger system (above the picture) that is being separated by gravity, forming long star tails. (Photo: Elena D'Onghia (CfA))

The team found that collisions between pairs of galaxies stimulated the gravity process they called 'stellar separation under gravity resonance' , leading to the separation of stars from small galaxies. more and turn it into a spherical dwarf galaxy.

'Like the oscillation of the universe, the collision causes gravity resonance, separating the stars and gas from the dwarf galaxy, forming the stellar tail and the long stellar bridge as we see it today,' D'Onghia explained.

Gurtina Besla, co-author of the study, adds: 'This mechanism explains the origin that leads to the most important characteristic of globular dwarf galaxies - why they are made mostly of dark matter.'

Star layers pulled out by gravity interaction can be detected during astronomical observations . For example, new stellar bridges are found between two closely spaced dwarf galaxies called Leo IV and Leo V which may be the product of stellar separation under gravity resonance.