Astronomers reveal new details about 'monster' star-forming galaxies

An international team of astronomers from Japan, Mexico and the University of Massachusetts Amherst studying a "monster galaxy" 12.4 billion light years away today report that their instruments have achieved a 10 times higher angular resolution than ever before, revealing galaxy structural details previously completely unknown. They also were able to analyze dynamic properties that could not be probed before. Details appear in Nature.

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Credit: National Astronomical Observatory of Japan

Artist's impression of the monster galaxy COSMOS-AzTEC-1. This galaxy is located 12.4 billion light-years away and is forming stars 1,000 times more rapidly than our Milky Way galaxy. ALMA observations revealed dense gas concentrations in the disk, and intense star formation in those concentrations.

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. Credit: ALMA (ESO/NAOJ/NRAO), Tadaki et al.

ALMA revealed the distribution of molecular gas (left) and dust particles (right). In addition to the dense cloud in the center, the research team found two dense clouds several thousand light-years away from the center. These dense clouds are dynamically unstable and thought to be the sites of intense star formation.

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The astronomers found something unusual: that the gas clouds in COSMOS-AzTEC-1 are very unstable

. As they point out, in a normal situation, internal gravity and external pressure are balanced. Once gravity overcomes the pressure, the gas cloud collapses and forms stars at a rapid pace.

Then, the stars and the supernova explosions at the end of the stellar life cycle expel gases, which increase the pressure towards the outside.

As a result, gravity and pressure reach a balanced state and the formation of stars continues at a moderate pace. But in COSMOS-AzTEC-1, the pressure is much weaker than gravity and difficult to balance.

Therefore, this galaxy shows the formation of stars out of control and has transformed into a "monstrous" unstoppable galaxy.