英文原文：Mystery Intergalactic Radio Bursts Detected

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An artist's impression of one of the radio wave bursts and the CSIRO Parkes radio telescope in Australia.

　科学家通过射电望远镜探索更加遥远的宇宙，距离我们数十亿光年的神秘射电波释放可能来自中子星或者黑洞

　　据国外媒体报道，澳大利亚联邦科学与工业研究机构(CSIRO)科学家通过帕克斯射电望远镜发现来自数十亿年前的神秘无线电波，并猜测其到底起源于何处。参与本项调查的国际研究小组认为该事件存在突然爆发的能量源，或来自一个极端的天体物理事件，比如中子星或者黑洞等。英格兰的曼彻斯特大学与CSIRO的研究人员丹·桑顿认为这个神秘的无线电波背后隐藏着巨大的质量或者能量，大约在六年前，科学家就发现银河系外出现来历不明的射电波发射，但是并没有确认那些信号到底是什么。

　　调查结果显示，它们来自银河系外的一次射电爆发，只有几毫秒的时间，距离我们却将近110亿光年之遥，令人惊讶的是我们仅仅是对一小部分天区进行了观测，马克斯·普朗克研究所所长、曼彻斯特大学教授迈克尔·克雷默认为这次神秘的爆发只有眨眼睛十分之一的功夫，而我们却是幸运的，在正确的时间和正确的地点观测到了这一现象。根据发表在《科学》杂志上的论文，科学家在调查的过程中排除了其他无线电脉冲源的干扰，根据亮度和能量确定其来自宇宙方向。

　　在过去的四年内，科学家们一直在寻找这个神秘宇宙天体爆发的来源，其特点是持续时间非常短，而且陆源射电源对宇宙源也会产生干扰，这给调查带来了极大的难度，根据本项研究的主要负责人丹·桑顿博士介绍：“鉴于调查的天区较小，如果我们能每天不间断地对夜空进行观测，那么会发现更多的神秘射电源，毫无疑问这个发现是幸运的。”图中显示的为艺术家绘制的宇宙单一射电源爆发的快速能量释放事件，位于地球上的射电望远镜可以探测到起源于遥远宇宙的射电波。

下面是原文：

Astronomers were on a celestial fishing expedition for pulsing neutron stars and other radio bursts when they found something unexpected in archived sky sweeps conducted by the Parkes radio telescope in New South Wales, Australia.

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The powerful signal, which lasted for just milliseconds, could have been a fluke, but then the team found three more equally energetic transient flashes all far removed from the galactic plane and coming from different points in the sky.

Analysis later indicated that, unlike most cosmic radio signals that originate in the Milky Way or a nearby neighbor galaxy, these four seem to have come from beyond.

Whatever triggered the bursts has come and gone. The signals, detected between February 2011 and January 2012, were one-time events so little follow-up work can be done.

What is known is that in just a few milliseconds, each of the signals released about as much energy as the sun emits in 300,000 years.

“They have come such a long way that by the time they reach the Earth, the Parkes telescope would have to operate for 1 million years to collect enough to have the equivalent energy of a flying mosquito,” astronomer Dan Thornton, with the University of Manchester in the United Kingdom, wrote in an email to Discovery News.

Scientists have all kinds of theories about what exotic phenomena may have triggered the bursts. The contenders include colliding magnetars, which are neutron stars with super-strong magnetic fields; evaporating black holes; and gamma ray bursts that involve a supernova.

Or, as Cornell University astronomer James Cordes points out, the bursts could be from an entirely new type of high-energy astrophysical event.

“It is still early days for identifying the astrophysical origins of such common but (so far) rarely detected events,” Cordes wrote in an article published in this week’s Science.

Whatever is happening is probably a relatively common, though difficult to detect, phenomenon. Extrapolating from the research, astronomers estimate there are as many as about 10,000 similar high-energy millisecond radio bursts happening across the sky every day.

“This might seem common, and it is, but you need a big telescope to detect them,” Thornton said.

Typically, telescopes only look at a very small patch of the sky at any one time, he added, “so you have to look for a long time before seeing many. This is why we have only detected a handful so far.”

Similar radio signals have been found before, but astronomers could never nail down whether they came from inside or beyond the galaxy.

Thornton and his team did so by characterizing the plasma the radio waves had to travel through before reaching the telescope. The shape of the wave is impacted by the amount of plasma along the signal’s path.

The astronomers found that these four signals traveled through more plasma than what could be accounted for by interstellar gas in the Milky Way.

They suspect the extra gas lies between galaxies, a finding that opens the door to a potential new technique to probe the contents of distant galaxies and why lies between them.

The research appears in this week’s Science.(Jul 4, 2013 02:00 PM ET // by Irene Klotz)