Farthest known galaxy in universe discovered

An international team of astronomers said Tuesday they have discovered the most distant galaxy ever measured in the universe.

By using a powerful instrument called MOSFIRE on the Keck I telescope at the Keck Observatory in Hawaii, the team determined that the galaxy, EGS-zs8-1, formed more than 13 billion years ago at a time when the universe was only five percent of its present age.

Only a handful of galaxies currently have accurate distances measured in this epoch of the universe and none younger than this, according to the team led by Yale and the University of California, Santa Cruz.

The galaxy, one of the brightest and most massive objects in the early universe, was originally identified based on its particular colors in images from the U.S. Hubble and Spitzer space telescopes.

The new measurement also enabled the astronomers to determine that EGS-zs8-1 was forming stars very rapidly, about 80 times faster than our galaxy today.

"While we saw the galaxy as it was 13 billion years ago, it had already built more than 15 percent of the mass of our own Milky Way today," lead author Pascal Oesch of the Yale University said in a statement. "But it had only 670 million years to do so. The universe was still very young then."

The observations see EGS-zs8-1 at a time when the universe was undergoing very important changes: the hydrogen between galaxies was transitioning from a neutral to an ionized state.

"It appears that the young stars in the early galaxies like EGS- zs8-1 were the main drivers for this transition called reionization," said Rychard Bouwens of the Leiden Observatory, co- author of the study.

The discovery, published in the U.S. journal Astrophysical Journal Letters, was only possible thanks to the relatively new MOSFIRE instrument on the Keck I telescope, which allows astronomers to efficiently study several galaxies at the same time. Endite