Washington: Most intense type of star-forming activity in the early Universe ultimately became the most massive galaxies in today’s cosmos, a new study has suggested.
Astronomers have combined observations from the LABOCA camera on the ESO-operated 12-metre Atacama Pathfinder Experiment (APEX) telescope with measurements made with ESO’s Very Large Telescope, NASA’s Spitzer Space Telescope, and others, to look at the way that bright, distant galaxies are gathered together in groups or clusters.
The more closely the galaxies are clustered, the more massive are their halos of dark matter — the invisible material that makes up the vast majority of a galaxy`s mass.
The new results are the most accurate clustering measurements ever made for this type of galaxy.
The galaxies are so distant that their light has taken around ten billion years to reach us, so we see them as they were about ten billion years ago.
In the snapshots from the early Universe, the galaxies can be seen undergoing the most intense type of star formation activity known, called a starburst.
By measuring the masses of the dark matter halos around the galaxies, and using computer simulations to study how these halos grow over time, the astronomers found that these distant starburst galaxies from the early cosmos eventually become giant elliptical galaxies — the most massive galaxies in today`s Universe.
“This is the first time that we’ve been able to show this clear link between the most energetic starbursting galaxies in the early Universe, and the most massive galaxies in the present day,” said Ryan Hickox (Dartmouth College, USA and Durham University, UK), the lead scientist of the team.
Furthermore, the new observations indicate that the bright starbursts in these distant galaxies last for a mere 100 million years — a very short time in cosmological terms — yet in this brief time they are able to double the quantity of stars in the galaxies.
The sudden end to this rapid growth is another episode in the history of galaxies that astronomers do not yet fully understand.
“We know that massive elliptical galaxies stopped producing stars rather suddenly a long time ago, and are now passive. And scientists are wondering what could possibly be powerful enough to shut down an entire galaxy`s starburst,” said Julie Wardlow (University of California at Irvine, USA and Durham University, UK), a member of the team.