With the power only to the Big Bang itself, shining with the luminosity of a billion, trillion Suns, an event with such intensity it could wipe out life on Earth of one were to off in our galactic neighbourhood. The gamma ray burst is the biggest outpouring of energy in the known universe caused when the most gigantic stars in the universe end their lives in a hypernova. The gamma ray burst is the birth cry of a massive black hole emerging into existence.
When one of these stars eventually starts running out of fuel in its core, it stars shedding material from it’s outer layers. When all the fuel in the core runs out, the star cannot support itself so all matter is pulled inwards creating runaway gravity and a spinning black hole is formed in the core. This spinning black hole has so much energy that two narrow jets of material shoot out from above and below the monstrous gravity in the core. These jets then burst out through the star’s surface travelling at 99.995% of light speed.
This highly concentrated narrow beam escapes from the self destructing star and slams into the surrounding gas clouds and interstellar medium, causing it to glow extremely brightly. This is the afterglow of the gamma ray burst that can be seen with telescopes and last for days or even weeks after. The actual burst itself only lasts for milliseconds or seconds, yet in this short space of time more energy is released than our Sun will emit in 10 billion years.
When the jets are pointing towards Earth we can pick them up, The Hete-2 Satellite is designed especially for this and can detect and localize bursts, studying them instantly for gamma rays and x-rays. Gamma ray bursts are actually very common and one goes off most days in the universe, but they are all at vast distances away usually billions of light years. Although they happen most days in the universe this makes them actaully very rare because considering the billions of galaxies out there, one a day in the cosmos isn’t very much. So the likely hood of a gamma ray burst going off in an average galaxy like the Milky Way is about 1 every 100,000 to 1,000,000 years, and if one were to go off in the Milky Way tomorrow then the jet would have to be pointed towards Earth to pose a danger. But if one was in the neighbourhood and one of the jets was pointed at Earth it would wreak havoc with the atmosphere and natural systems of our planet causing a mass extinction.
There are some very dangerous and destructive phenomena out there in the cosmos and these beasts are top of the list. Like thermonuclear flash bulbs they have the power to wipe out life on nearby planets, sterilising their local galactic environment, and stopping emerging civilisation in their tracks. In our Galaxy there are no obvious contenders for a gamma ray blast in the Sun’s vicinity so we are pretty safe.
As with a lot of discoveries gamma ray bursts in space were found by accident. In the 1960′s the world was a bit jittery over what countries had the nuclear bomb, and what they were intending to do with their new toys. Satellites started to get put into orbit to keep an eye on other countries making sure they weren’t carrying out secret tests. These were the Vela Satellites launched in 1967 and were designed to detect the gamma rays emitted during a nuclear explosion. Horror ensued when strong gamma ray sources started to be detected going off at random points. But horror soon turned to bewilderment when it was realised that the sources of the outbursts were not from the Russians on Earth, but coming from deep space and at random points in the sky.
It was at this point that the mystery was handed over to the astronomers to puzzle over. But at this point nobody knew what these strange and powerful events were. All types of explanations were put forward, neutron stars colliding, black holes merging. Finally in 1997 the first visible after glow and x-rays were measured, including the gamma ray burst’s redshift to work out distance. It was at this point that these events were at vast distances away, and associated with the deaths of the most gigantic stars in the universe.