nts in the universe: messages from the beginning of time when the most massive stars in existence violently collapsed. It was only with the advent of more advanced telescopes that GRBs started to reveal more about themselves.
The Compton X-Ray Observatory found that GRBs came from all over the sky and astronomers realized they must be extragalactic. Advanced telescopes which quickly pinpointed the precise location of a GRB led to the detection of faint afterglows all across the electromagnetic range. In every case, the GRB came from the same direction
as a very distant galaxy.
as a very distant galaxy.
But extensive observations revealed a lot more. By measuring how much the light had been red-shifted by the expansion of the universe, astronomers could estimate their distances. They concluded that the light from GRBs had been traveling for over half the age of the universe; they were among the most distant objects ever seen. But to be so far away and remain the brightest thing in the sky meant an unimaginable amount of energy had to be producing these flashes.
An exceptionally massive dying star can collapse into a black hole without triggering a supernova. With the sudden removal of the stellar core, the upper layers of the star collapse down to fill in the cavity. If the star is spinning rapidly, the falling matter is whipped up into a spinning fury. In the ensuing vortex, superheated plasma is entangled by highly twisted magnetic fields. Like an electromagnetic cannon, jets of gas blast through the poles of the star and erupt into space. The tunnel through the star forces the plasma streams into narrow cones, tightly focusing the energy of the collapse.
If one of these jets is pointed towards Earth, we see it as a brilliant flash of gamma ray light that fades after only a few seconds. Fortunately, all the GRBs detected have been at safe distances from Earth. The closest, detected about a decade ago, is still over a billion light-years away. If a GRB were to erupt in our own galaxy it could be very troubling for humanity. Directed right at Earth, it could quite possibly trigger a mass extinction or sterilization of the planet. In fact, there is evidence to suggest that GRBs could very well be responsible for one extinction event 450 million years ago.
Gamma ray bursts call out to us from deep within the cosmos. They are echoes from the beginning of time, faint beacons from the furious implosion of stellar giants. Thanks to advancements in detectors and telescopes, these galactic lighthouses are no more a stranger to us.
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