這是宇宙？

Astronomers have discovered the largest known structure in the universe, a clump of active galactic cores that stretches 4 billion light-years from end to end.

The structure is a large quasar group (LQG), a collection of extremely luminous galactic nuclei powered by supermassive central black holes. This particular group is so large that it challenges modern cosmological theory, researchers said.

"While it is difficult to fathom the scale of this LQG, we can say quite definitely it is the largest structure ever seen in the entire universe," lead author Roger Clowes, of the University of Central Lancashire in England, said in a statement. "This is hugely exciting, not least because it runs counter to our current understanding of the scale of the universe."

Quasars are the brightest objects in the universe. For decades, astronomers have known that they tend to assemble in huge groups, some of which are more than 600 million light-years wide.

But the record-breaking quasar group, which Clowes and his team spotted in data gathered by the Sloan Digital Sky Survey, is on another scale altogether. The newfound LQC is composed of 73 quasars and spans about 1.6 billion light-years in most directions, though it is 4 billion light-years across at its widest point.

To put that mind-boggling size into perspective, the disk of the Milky Way galaxy — home of Earth's solar system — is about 100,000 light-years wide. And the Milky Way is separated from its nearest galactic neighbor, Andromeda, by about 2.5 million light-years.

The newly discovered LQC is so enormous, in fact, that theory predicts it shouldn't exist, researchers said. The quasar group appears to violate a widely accepted assumption known as the cosmological principle, which holds that the universe is essentially homogeneous when viewed at a sufficiently large scale.  

Calculations suggest that structures larger than about 1.2 billion light-years should not exist, researchers said.

"Our team has been looking at similar cases which add further weight to this challenge, and we will be continuing to investigate these fascinating phenomena," Clowes said.

The new study was published today (Jan. 11) in the Monthly Notices of the Royal Astronomical Society.

Follow SPACE.com senior writer Mike Wall on Twitter @michaeldwall or SPACE.com@Spacedotcom. We're also on Facebook and Google+. 

藉助 Google，試翻一下：

什麼新聞也沒這個大，別太認真！:)

天文學家已經發現了宇宙中已知最大的結構，一叢活動的星系核，從端到端綿延40億光年年。

結構是一個大的類星體組（LQG），電中央的超大質量黑洞非常明亮的星系核的集合。這個特殊的群體是如此之大，它挑戰了現代宇宙學理論，研究人員如是說。

「雖然是很難捉摸這LQG的規模，我們可以說相當肯定，它是在整個宇宙中見過的最大的結構」，第一作者Roger Clowes，在英國中央蘭開夏大學在一份聲明中說。「這是非常令人興奮的，因為它違背了我們目前的了解宇宙的規模。」

類星體是宇宙中最明亮的天體。幾十年來，天文學家已經知道，他們往往聚集在龐大的群體，其中有一些是超過6億光年寬。

但破紀錄的類星體，Clowes和他的團隊發現了斯隆數字巡天計劃所收集的數據，是完全在另一個規模。新發現的LQC是由73個類星體，各方向跨度約16億光年，但它的最大跨度約是40億光年。

令人難以置信的大小，角度，銀河系的磁碟地球上的太陽能系統-家庭-大約10萬光年寬。和分離其最近的銀河系鄰居，仙女座星系，約2.5百萬光年的銀河系。

新發現的LQC是如此巨大，實際上，這理論預測它不應該存在的，研究人員說。類星體似乎違反了一個被廣泛接受的假設被稱為宇宙學原理，認為宇宙在一個足夠大的規模里，本質上是均勻的。

計算表明，大於約12億光年的結構不應該存在的，研究人員說。

Clowes表示：「我們的團隊一直在類似的情況下，進一步增加重量這一挑戰，我們將繼續調查這些迷人的現象，」。

今日（1月11日）的英國皇家天文學會月刊「上的這項新的研究發表。