It would seem sensible to seek the source of these in the universe's most conspicuous energy factories: quasars and gamma-ray bursts billions of light-years away from Earth.

在宇宙中最引人注目的能量工厂——距离地球数十亿光年的类星体和伽马射线爆发——中寻找这些物质的来源似乎是明智的。

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When the same source flared again after a 45 minute pause it was clear this event was not a typical gamma-ray burst.

当 45 分钟的停顿之后同一源头再次爆发时，很显然这一事件并非通常的伽马射线爆发。

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Interestingly, an April 18 paper in the journal Nature reported that upper limits for neutrinos measured from IceCube are low enough that gamma-ray bursts are unlikely to be the sole source of ultra-high energy cosmic rays.

CNN: Why gamma-ray burst shocked scientists