12 April 2011

New discovery sheds light on the early Universe

A team of astronomers, including Brahe Fellow Johan Richard from the Dark Cosmology Centre, have discovered a distant galaxy whose stars were created earlier in the history of the universe than previously observed. It sheds new light on the formation of the first galaxies and the evolution of the universe.

The galaxy was observed with the Hubble Space Telescope and NASA's Spitzer Space Telescope. The observations are very detailed, because the galaxy is visible through a cluster of galaxies, called Abell 383. It is this lucky situation that this galaxy cluster lies between Earth and the galaxy and amplifies the light and makes it possible to observe the galaxy, which otherwise would have been too faint to see.

The results have been published in the Monthly Notices of the Royal Astronomical Society.

The galaxy is visible through a cluster of thousands of galaxies called Abell 383, which has such a strong gravitational pull that the light that the galaxies behind it emit is deflected and focused. The phenomenon is called gravitational lensing and acts like a magnifying glass. This galaxy cluster strongly amplifies the light and makes it possible to observe the galaxy, which would have otherwise been too faint to see.

The measurements of the light showed that when the galaxy emitted the light that we are currently seeing the universe was about 950 million years old.