Ancient Dwarf Starburst Galaxies Helped a Young Universe Grow

Ancient star-forming "starburst" dwarf galaxies likely formed a great deal of the Universe we see today, according to new observations for NASA's Hubble Space Telescope.

A specific type of small and super-dense dwarf galaxies offer evidence that they may have helped form a significant number of the Universe's stars.

"We already suspected these kinds of galaxies would contribute to the early wave of star formation, but this is the first time we've been able to measure the effect they actually had," Hakim Atek of the école Polytechnique Fédérale de Lausanne (EPFL) in Switzerland said in a statement.

Atek is the lead author of a new study that investigates how much of a role dwarf galaxies had at the beginning of the Universe.

Unlike large galaxies, dwarf galaxies take up a significantly small amount of space. However, they are hyper-dense, boasting a surprising number of stars for their small size. Past research has indicated that most dwarf galaxies don't exist in the older portion of the Universe because as the Universe began to expand, these galaxies would collide with one another, literally throwing stars and developing the large and more spacious galaxies we see today.

According to new findings published in the Astrophysical Journal, "starburst" dwarf galaxies in particular can pump out so many stars in such a short amount of time that it would be ludicrous to assume that most stars in the Universe came from elsewhere.

In-fact, the scientists determined that if the Universe first formed stars at the rate that average galaxies currently produce them, there would be a significantly less number of stars in the sky, compared to what we see.

"These galaxies are forming stars so quickly that they could actually double their entire mass of stars in only 150 million years - an incredibly short astronomical timescale," explained co-author Jean-Paul Kneib.

According to Kneib, most galaxies wind up doubling their mass in one to three billion years, not a mere hundred million.

The authors of the study admit that there are very few starburst class dwarf galaxies that can be found, suggesting that either they are formed in very unusual instances, or are simply degraded into many larger and less dense galaxies following the collisions that were so common at the Universe's start. 

The study was published in June 19 online issue of The Astrophysical Journal.

[Credit: ESA/Hubble]