29 May 2011

Earliest gamma-ray burst discovered

Gamma-ray bursts (GRBs) serve as a unique tool to study the first galaxies. Due to their extreme brightness they can be seen even at extreme distances. Hence, they function as glow-worms that briefly turns on and reveals the position of the explosion site of a massive star far away.

Discovery images of the GRB 090429B afterglow

Astronomers at DARK have contributed to the discovery of a gamma-ray burst (GRB) that occurred only about 500 million years after the Big Bang. Analysis of the GRB from the 29th of April 2009, recently accepted for publication in the Astrophysical Journal, show that this explosion occurred only about 500 million years of the Big Bang, at a redshift of 9.4. Hence, it is the most distant GRB known to man.

This important discovery shows that GRBs from these early generations of stars appear similar to GRBs that occur later in the history of the Universe, and it pinpoints the location of one of the earliest galaxies formed in Universe known to man.

Observing galaxies

Observing galaxies to understand the development of the Universe
When we look out in the Universe, away from the densest regions of our own cosmic habitat, the Milky Way, we see Galaxies. Why do galaxies exist, what are the properties of galaxies, when and how did they form, how do they evolve, and in which variety have they exist d throughout the cosmic ages? The answers to these questions are not known, but during the last 10-15 years astronomers have made significant progress.

The unique advantage of astrophysics is that the history of the Universe is available for observation due to the finite speed of light. In principle we just have to observe a sufficiently distant part of the Universe to look back to the epoch when galaxies first appeared. It may sound incredible that we should be able to look back more than 13 billion years to when the first galaxies formed, but this is what is becoming technically possible with stronger land- and satellite-based telescopes.