Multicolor space nebula
March 14, 2012

The Feeding Habits Of Teenage Galaxies

It has been widely known by astronomers that the earliest galaxies were much smaller than the large spiral and elliptical galaxies that exist now. As galaxies grow, they eat and put on weight, but exactly how they do this remains a mystery. Looking at a few, very carefully selected galaxies, astronomers are conducting a survey to determine how these galaxies grew during their “teenage” years, or the period between 3 and 5 billion years after the big bang theory.

The team of international team is using state-of-the-art technology found on the European Southern Observatory´s Very Large Telescope (VLT) to collect data about what happened during those billions of years after the Big Bang. The survey is called MASSIV, or Mass Assembly Survey with SINFONI in VVDS. (SINFONI and VVDS refer to the instruments and technology being used on the VLT).

According to a press release about their research, the team says they have collected the largest and most detail-enriched data about the gas-rich galaxies in their early stages of growth.

The research team is going through this mass amount of data and learning all they can about the ways galaxies will consume in order to grow.

“Two different ways of growing galaxies are competing: violent merging events when larger galaxies eat smaller ones, or a smoother and continuous flow of gas onto galaxies. Both can lead to lots of new stars being created,” explains Thierry Contini ,who leads the work.

So far, the team has discovered that a smooth gas flow was an important factor in feeding these galaxies during the period 3-5 billion years after the Big Bang. As time went on and these galaxies grew larger, mergers of galaxies became more important.

“To understand how galaxies grew and evolved we need to look at them in the greatest possible detail. The SINFONI instrument on ESO´s VLT is one of the most powerful tools in the world to dissect young and distant galaxies. It plays the same role that a microscope does for a biologist,” adds Contini.

Using the technology available on the VLT and the high quality images it produces, the team is able to make maps based on how the galaxies are moving, growing, and evolving. While these galaxies appear to be tiny, faint blobs in the sky when viewed without the use of the VLT, the images produced by the telescope give scientists a look into the exact makeup of these galaxies. They did not expect the results they found.

Benoit Epinat, another member of the team, said “For me, the biggest surprise was the discovery of many galaxies with no rotation of their gas. Such galaxies are not observed in the nearby Universe. None of the current theories predict these objects.”

“We also didn´t expect that so many of the young galaxies in the survey would have heavier elements concentrated in their outer parts – this is the exact opposite of what we see in galaxies today,” adds Contini.

While the team has only begun the research into the feeding habits of galaxies, they plan to implement the same technology they are using on future telescopes and instruments, such as the European Extremely Large Telescope.


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