News Release Archive:

News Release 43 of 129

August 5, 2009 01:00 PM (EDT)

News Release Number: STScI-2009-24

Astronomers Find Hyperactive Galaxies in the Early Universe

The full news release story:

Astronomers Find Hyperactive Galaxies in the Early UniverseView this image


The fast-moving stars shed new light on how these distant galaxies, which are a fraction the size of our Milky Way, may have evolved into the full-grown galaxies seen around us today. The results will be published in the August 6, 2009 issue of the journal Nature, with a companion paper in the Astrophysical Journal.

"This galaxy is very small, but the stars are whizzing around as if they were in a giant galaxy that we would find closer to us and not so far back in time," says Pieter van Dokkum, professor of astronomy and physics at Yale University in New Haven, Conn., who led the study. It is still not understood how galaxies like these, with so much mass in such a small volume, can form in the early universe and then evolve into the galaxies we see in the more contemporary, nearby universe, which is about 13.7 billion years old.


"By looking at this galaxy we are able to look back in time and see what galaxies looked like in the distant past when the universe was very young," says team member Mariska Kriek of Princeton University in Princeton, N.J. 1255-0 is so far away that the universe was only about 3 billion years old when its light was emitted.


To witness the formation of these extreme galaxies astronomers plan to observe galaxies even farther back in time in great detail. By using the Wide Field Camera 3, which was recently installed on the Hubble Space Telescope, such objects should be detectable. "The ancestors of these extreme galaxies should have quite spectacular properties as they probably formed a huge amount of stars, in addition to a massive black hole, in a relatively short amount of time," says van Dokkum.

This research follows recent studies revealing that the oldest, most luminous galaxies in the early universe are very compact yet surprisingly have stellar masses similar to those of present-day elliptical galaxies. The most massive galaxies we see in the local universe (where we don't look back in time significantly) that have a mass similar to 1255-0 are typically five times larger than the young compact galaxy. How galaxies grew so much in the past 10 billion years is an active area of research, and understanding the dynamics in these young compact galaxies is a key piece of evidence in eventually solving this puzzle.

The Hubble Space Telescope observations were made with the Near Infrared Camera and Multi-Object Spectrometer (NICMOS).

The Gemini observations were made using the Gemini Near Infrared Spectrograph (GNIRS), which is currently undergoing upgrades and will be reinstalled on the Gemini North telescope on Mauna Kea in 2010.

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Ray Villard
Space Telescope Science Institute, Baltimore, Md.

Peter Michaud
Gemini Observatory, Hilo, Hawaii