Growing galaxies gently
New observations from ESO”â„¢s Very Large Telescope have, for the first time, provided direct evidence that young galaxies can grow by sucking in the cool gas around them and using it as fuel for the formation of many new stars. In the first few billion years after the Big Bang, the mass of a typical galaxy increased dramatically, and understanding why this happened is one of the hottest problems in modern astrophysics.
The first galaxies formed well before the Universe was one billion years old and were much smaller than the giant systems “” including the Milky Way “” that we see today. Somehow, the average galaxy size has increased as the Universe has evolved. Galaxies often collide and then merge to form larger systems, and this process is certainly an important growth mechanism. However, an additional, gentler way has been proposed.
Says astronomy team leader Giovanni Cresci: “The new results from the VLT are the first direct evidence that the accretion of pristine gas really happened, and was enough to fuel vigorous star formation and the growth of massive galaxies in the young Universe.”Â The discovery will have a major impact on our understanding of the evolution of the Universe from the Big Bang to the present day. Theories of galaxy formation and evolution may have to be re-written.
Credit: ESO/L CalÃƒÂ§ada