It was bright, fierce and thankfully short. A mysterious event in a distant galaxy has blasted our solar system with the most powerful burst of X-rays ever recorded, temporarily blinding an astronomical satellite.
At 0303聽GMT on 21聽June, a sudden burst of X-rays struck the , the mission team .
X-rays from space are absorbed by Earth鈥檚 atmosphere, so pose no danger on the ground. However, Swift orbits Earth at an altitude of 600聽kilometres, where the blast was so intense that it overwhelmed the spacecraft鈥檚 X-ray detector. It also confused the software that analyses the mission鈥檚 data on the ground, says of Pennsylvania State University in University Park, the mission鈥檚 chief scientist.
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鈥淸The software] basically threw up its hands and said, 鈥楽omething must be wrong, because the data doesn鈥檛 make sense,'鈥� he says.
Puzzling pummelling
Swift鈥檚 records show that at its peak, the burst pummelled the spacecraft with 143,000 X-ray photons per second. That made it nearly 15 times as bright as Scorpius X-1, a neutron star 9000 light years from Earth that is normally the brightest X-ray object in the sky. The burst dimmed rapidly during its first few seconds but continued glowing for about 10 minutes.
This powerful beginning was probably the most powerful X-ray flash ever recorded, Burrows says. An may have appeared brighter 鈥� the comparison is hard to make because the 1979 flash was observed by a different spacecraft 鈥� but only because it occurred in a nearby galaxy, just 160,000 light years from Earth. By contrast, the June flash was traced to a vastly more distant galaxy 5聽billion light-years away.
No one knows what caused the burst, but a clue lies in the fact that it accompanied a lengthy burst of gamma rays from deep space. Swift鈥檚 purpose is to determine the origin of such bursts using three telescopes that detect gamma rays, X-rays, and ultraviolet and visible light. Long gamma-ray bursts are thought to be due to jets of matter shooting out almost at the speed of light from a star that is collapsing to form a black hole: the same type of event may have caused the recent X-ray burst.
However, shock waves from these violent events normally produce around 10 to 100 X-ray photons per second, so the Swift team is at a loss to explain why this X-ray burst was more than 1000 times brighter than this.
鈥淲e鈥檙e very puzzled 鈥� we don鈥檛 understand it yet,鈥� Burrows says. 鈥淓very once in a while something comes along that鈥檚 completely unexpected and this is one of them.鈥�
