New GRB becomes the most distant object known

A Gamma Ray Burst (GRB) that was detected on the 23rd April 2009 has led to the discovery of the most distant object known in the Universe. By studying the infra-red light from an object found at the position of the GRB, astronomers have calculated that it is an incredible 13 billion light years away. This is to say that the explosion actually happened 13 billion years ago, but we have only just found out now because the light has taken that long to reach us. From what we currently think about the age of the Universe, this means that the burst occurred when it was only 630 million years old, a mere one-twentieth of its current age.

Image of the GRB site
Infra-red image of the most distant object in the Universe (circled)
Credit: Gemini North Telescope

GRBs are super-massive bursts of energy that can be seen over great distances. Astronomers believe this particular burst of energy, known as GRB 090423, occured during the explosion of an extremely massive star - an event known as a supernova. The results of the explosion will be visible for several days and will most likely have led to the formation of a small black-hole in the place where the star used to be.

Although the burst only lasted for 10 seconds, it was immediately detected by the Swift Satellite, which quickly directed ground-based observatories to observe the new target. The spectrum of the object was then used to calculate the redshift of the object. Redshift is the measure astronomers use to deduce the distance of far off objects, like galaxies.

Graph of distant objects
Graph showing the age of the GRB in relation to previously known objects
Credit: Edo Berger Harvard/CfA

From the above graph, it can be seen that the new discovery is way ahead of all previously known 'most distant' objects, and comes from a chaotic time during the early history of the Universe when galaxies were just starting to form.