Cosmic Magnification Throws Light on Most Distant Galaxy

The most distant galaxy has been discovered by the combined power of NASA's Spitzer and Hubble space telescopes as well as a cosmic magnification effect.

The team of astronomers was led by Wei Zheng of the Johns Hopkins University.

The light from the young galaxy was captured when the universe was 13.7 billion year old and was 500 million years old. The far off galaxy existed during the dark age, when the universe was transformed from a dark starless expanse to a identifiable cosmos full of galaxies. This new discovery leads to the deepest, remotest epochs of cosmic history.

"This galaxy is the most distant object we have ever observed with high confidence," said Zheng, a principal research scientist in The Henry A. Rowland Department of Physics and Astronomy at Johns Hopkins' Krieger School of Arts and Sciences and lead author of a paper appearing in Nature on Sept. 20. "Future work involving this galaxy -- as well as others like it that we hope to find -- will allow us to study the universe's earliest objects and how the Dark Ages ended."

Light from the primordial galaxy traveled approximately 13.2 billion light-years before reaching NASA's telescopes.

The Hubble Space Telescope registered the newly described far-flung galaxy in four wavelength bands. Spitzer located it in a fifth band with its Infrared Array Camera (IRAC), placing the discovery on firmer ground.

In order to track these distant galaxies the astronomers use the gravitational lensing. Based on the Spitzer and Hubble observations, astronomers think the distant galaxy was spied at a time when it was less than 200 million years old. It also is small and compact, containing only about 1 percent of the Milky Way's mass. 

According to leading cosmological theories, "The first galaxies should indeed have started out tiny. They then progressively merged, eventually accumulating into the sizable galaxies of the more modern universe."

"In essence, during the epoch of reionization, the lights came on in the universe," said paper co-author Leonidas Moustakas, a research scientist at NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif.

Holland Ford, one of Zheng's colleagues and a co-author on the paper, commented on the findings.

"Science is very exciting when we explore the frontiers of knowledge," said Ford, a physics and astronomy professor at Johns Hopkins. "One of these frontiers is the first few hundred million years after the birth of our universe. Dr. Zheng's many years of searching for quasars and galaxies in the dawn of the universe has paid off with his discovery of a galaxy that we see as it was when the universe was less than 500 million years old.

"With his discovery, we are seeing a galaxy when it was not even a toddler," Ford said. "But this infant galaxy will in its future grow to be a galaxy like our own, hopefully hosting planetary systems with astronomers who will look back in time and see our galaxy in its infancy."