On April 23, the Swift X- ray satellite witnessed a record-breaking gamma ray burst (G R B), a blast that signals the explosive death of a massive star. Swift saw 10 seconds of gamma rays followed by an X-ray after glow. Such afterglows occur because the star's gamma-ray jets plow through surrounding material that has star previoulst shed. As they barrel through, the gamma rays transfer energy to the material and cause it to radiate. After localizing its position with Swift, and then performing follow-up observations with multiple ground based observatories, scientists determined that the burst called GRB 0800423, occurred when the universe was just one 630 million years old. (That corresponds to a red shift of 8.2)
The recorded red shift makes this GRB the most distant blast yet seen. The object's red shift corresponds to when the universe was just one-twentieth of its current age. Astronomers believethe first stars began forming around 200 million years after the Big bang, and GRB 090423's progenitor stars brings them closer to that time period.
It also gives astronomers clues about the little understood cosmic Dark Ages, and the following "reionization"epoch.
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