Distant galaxy opens window into the early universe
September 24, 2012
A team of Johns Hopkins University astronomers have spotted what may well be the most distant galaxy ever detected. Dubbed "MACS 1149-JD", the discovery provides insight into the most remote epoch of cosmic history, as light captured from the faint galaxy shone forth when the universe was just 500 million years old – or 3.6 percent of its present age.
The Johns Hopkins University astronomers believe the distant MACS 1149-JD galaxy to have been observed at a time when it was less than 200 million years old, and it is further thought to be amongst the galaxies which played an important role in the epoch of reionization, the event that signaled the end of the universe’s so called "Dark Ages."
"In essence, during the epoch of reionization, the lights came on in the universe," explains paper co-author Leonidas Moustakas, a research scientist at NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, California.
As predicted in Albert Einstein's general theory of relatively, gravitational lensing allows astronomers to view objects further away than would otherwise be possible, by making use of the gravity of foreground objects which warp and magnify the light from background objects. In this case, a massive galaxy cluster situated between our own galaxy and the early galaxy magnified the latter's light, making the remote object approximately 15 times brighter.
"This galaxy is the most distant object we have ever observed with high confidence," said Wei Zheng, principal research scientist at The Henry A. Rowland Department of Physics and Astronomy at Johns Hopkins' Krieger School of Arts and Sciences, and lead author of a paper which appeared in Nature on September 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."
The remote galaxy is small and compact, containing only around one percent of the Milky Way’s mass, and this fits in with leading cosmological theories which posit that during the universe's infancy, initial galaxies indeed started out very small, before progressively merging and accumulating into the sizable galaxies of the later universe.
Astronomers plan to further study the rise of the first stars and galaxies, and the epoch of reionization, with Spitzer and Hubble’s successor – NASA's James Webb Telescope, slated for launch in 2018.
Source: Johns Hopkins University