Hubble to view the host galaxy

Apr 12, 2008 07:47 GMT  ·  By
Image showing the relative position of the brightest supernova explosion in the universe
   Image showing the relative position of the brightest supernova explosion in the universe

Three weeks ago, the Swift satellite detected the brightest gamma-ray burst in the visible universe in a galaxy located more than 7 billion light years away from Earth. It is though that the supernova explosion could have been the result of the collapse of a massive star into a black hole, and that, during the explosion, its brightness outpowered that of the Milky Way by at least five million times. Yet, after three weeks, the gamma-ray emission of the supernova is still powerful enough to outshine its parent galaxy.

The supernova explosion was first detected on 19 March, when it experienced five powerful gamma-ray bursts. What is believed to be the death of a star 50 times more massive than our Sun became, for a brief period of time, the most distant object in the universe to be viewed with the naked eye. The brightest explosion previously detected, in 2005, was told to have been 2.5 million times less bright than that observed on 19 March.

On 7 April, astronomers pointed the Hubble Space Telescope towards the point in space where the bright gamma-ray emission had been observed, in order to view the parent galaxy. Nevertheless, they were baffled by the fact that the light emissions coming from the source were still brighter than the galaxy itself. Gamma-ray emissions along with visible light are produced during supernova explosions, as matter from the star is ejected into space at relativistic speeds. However, in order to be observed from Earth, these emissions must first point towards our planet.

Focused jets

Gamma-rays are the most powerful type of electromagnetic waves in the universe, carrying massive amounts of energy as they travel through space. Some theories about how gamma-rays acquire such high brightness during supernova explosions suggest that focused jets of matter may be responsible; these would provide with an initial enhanced brightness that fades away as the jets slow down to lower speeds. Gamma-ray bursts experience a high brightness for short amounts of time and subsequently they fade away relatively fast.

Even if the focused jets cannot account for the gamma-ray bursts, the supernova explosions would have had to be extremely powerful to produce such a high brightness. "It's looking like a serious problem," said University of Leicester researcher, Nial Tanvir. Another possibility would be that the explosion must have converted, through some unknown process, more energy into gamma-ray radiation, but these are only speculations until Hubble is able to view the host galaxy.