Dramatic 'Blow Out' Phase of Galactic Evolution Revealed for First Time

by Bidita Debnath on Dec 8 2014 9:22 PM

Recently, astronomers were able to reveal the dramatic "blow out" phase of galactic evolution for the first time.
The astronomers have discovered dense gas being blasted out of a compact galaxy (called SDSS J0905+57) at speeds of up to two million miles per hour.

The gas was being driven to distances of tens of thousands of light years by the intense pressure exerted on it by the radiation of stars that are forming rapidly at the galaxy's centre. This was having a major impact on the evolution of the galaxy.

The team used the Institut de Radioastronomie Millimetrique (IRAM) Plateau de Bure Interferometer, a radio telescope based in the French Alps.

By detecting the molecule carbon monoxide, they were able to infer the amount of hydrogen gas present. Stars are born from clouds of hydrogen, so by removing this gas the galaxy can rapidly shut down its star formation. There was enough gas in the outflowing material to form the equivalent of over a billion Suns.

Dr Geachsaid that witnessing the aggressive termination of star formation, and the mechanism by which this was happening was an important new clue in the understanding of the evolution of galaxies.

Outflows of warm, ionized gas from galaxies are well known, but the team's observation of large amounts of cold, dense gas being violently removed from the central regions of the galaxy and far into space was a new discovery.

Previously it was not known whether the stars alone could drive out gas in this way. Instead, it was thought that energy associated with a growing central black hole would be required, but this was known not to be happening in SDSS J0905+57, so these results provided important new insights into how the growth of stars was regulated in galaxies.