Phoenix cluster sets `fastest star formation` record

London - With the help of world-class observatories, astronomers have discovered an extraordinary galaxy cluster, one of the largest objects in the universe that is breaking several important cosmic records.

Stars are forming in the Phoenix cluster at the highest rate ever observed for the middle of a galaxy cluster.

The object also is the most powerful producer of X-rays of any known cluster and among the most massive. The data also suggest the rate of hot gas cooling in the central regions of the cluster is the largest ever observed.

The Phoenix cluster is located about 5.7 billion light years from Earth. It is named not only for the constellation in which it is located, but also for its remarkable properties.

This amazing cluster was observed with NASA’s Chandra X-ray Observatory, the National Science Foundation’s South Pole Telescope, and eight other world-class observatories.

“While galaxies at the center of most clusters may have been dormant for billions of years, the central galaxy in this cluster seems to have come back to life with a new burst of star formation,” said Michael McDonald, a Hubble Fellow at the Massachusetts Institute of Technology and the lead author of a paper.

“The mythology of the Phoenix, a bird rising from the dead, is a great way to describe this revived object,” he added.

Like other galaxy clusters, Phoenix contains a vast reservoir of hot gas, which itself holds more normal matter -- not dark matter -- than all of the galaxies in the cluster combined. This reservoir can be detected only with X-ray telescopes such as Chandra.

With its black hole not producing powerful enough jets, the center of the Phoenix cluster is buzzing with stars that are forming about 20 times faster than in the Perseus cluster. This rate is the highest seen in the center of a galaxy cluster but not the highest seen anywhere in the universe. However, other areas with the highest star formation rates, located outside clusters, have rates only about twice as high. 

The frenetic pace of star birth and cooling of gas in the Phoenix cluster are causing the galaxy and the black hole to add mass very quickly -- an important phase the researchers predict will be relatively short-lived.

Remarkably, the Phoenix cluster and its central galaxy and supermassive black hole are already among the most massive known objects of their type. Because of their tremendous size, galaxy clusters are crucial objects for studying cosmology and galaxy evolution, so finding one with such extreme properties like the Phoenix cluster is important.

The findings appeared in the recent issue of the journal Nature.