VOA科学技术2023--Researchers Detect Ancient Energetic Burst

Researchers Detect Ancient Energetic Burst

Astronomers² have detected radio waves coming from what looks like a joining of galaxies³ from about 8 billion years ago. The discovery is the oldest-known example of an event that is difficult to explain: a fast radio burst.

In less than a millisecond, this burst released the amount of energy our sun releases in thirty years, scientists said.

The Australian SKA Pathfinder, a radio telescope in the state of Western Australia, detected the burst. And the European Southern Observatory's Very Large Telescope in Chile, one of the most powerful telescopes, found the location of the burst.

A fast radio burst, or FRB, is a kind of radio-frequency electromagnetic radiation. It lasts less than a millisecond but outshines most other sources of radio waves in the universe. Radio waves have the longest wavelengths⁴ in the electromagnetic spectrum⁵.

Ryan Shannon, an astronomer¹ at Swinburne University of Technology in Australia, was a co-leader of the study published recently in Science.

He said radio waves in FRBs are similar to those used in microwave ovens. And he added that this FRB had the same amount of energy needed to microwave "a bowl of popcorn⁶ twice the size of the sun."

Until now, the oldest-known such burst dated to 5 billion years ago, making this one 3 billion years older. The universe is about 13.8 billion years old. For comparison, Earth is about 4.5 billion years old.

In seeing objects and events from long ago, researchers look across large distances, making this burst also the farthest of any FRB ever detected.

"We now know that fast radio bursts have been around for more than half the age of the universe," said study co-leader Stuart Ryder of Macquarie University in Australia.

Researchers first discovered fast radio bursts in 2007.

The most likely source is a special kind of "neutron⁷ star, called a magnetar. These stars ... are some of the most extreme objects in the universe, which you would need to produce such extreme bursts," Shannon said.

"There are more energetic events in the universe, associated with stellar explosions or a black hole shredding⁹ a star apart. But FRBs are unique in that they produce all their energy in radio waves, with nothing seen in other bands - optical light or X-rays for example - and that the signals are so short," Shannon added.

They also are more common, Shannon explained, with around 100,000 thought to happen somewhere in the universe daily. Far fewer have been detected, Shannon said, and only around 50 - including this one - have been traced back to the galaxy¹⁰ where they began.

The scientists said that studying these bursts can help to detect and measure the large amount of matter believed to populate the large distances of space between galaxies.

Words in This Story

detect -- v. to discover or notice the presence of something

burst – n. a short period of producing or doing something that begins suddenly

millisecond – n. one-thousandth of a second

location -- n. a place or position

neutron star – n. a small and very dense¹¹ kind of stellar object

stellar – adj. of or relating to the stars

shred⁸ – v. to cut or tear (something) into long pieces

unique -- adj. used to say that something or someone is unlike anything or anyone else

trace -- v. to follow something back to its cause or beginning

1 astronomer   

n.天文学家

参考例句：

• A new star attracted the notice of the astronomer.新发现的一颗星引起了那位天文学家的注意。
• He is reputed to have been a good astronomer.他以一个优秀的天文学者闻名于世。

2 astronomers   

n.天文学者，天文学家( astronomer的名词复数 )

参考例句：

• Astronomers can accurately foretell the date,time,and length of future eclipses. 天文学家能精确地预告未来日食月食的日期、时刻和时长。 来自《简明英汉词典》
• Astronomers used to ask why only Saturn has rings. 天文学家们过去一直感到奇怪，为什么只有土星有光环。 来自《简明英汉词典》

3 galaxies   

星系( galaxy的名词复数 )； 银河系； 一群（杰出或著名的人物）

参考例句：

• Quasars are the highly energetic cores of distant galaxies. 类星体是遥远星系的极为活跃的核心体。
• We still don't know how many galaxies there are in the universe. 我们还不知道宇宙中有多少个星系。

4 wavelengths   

n.波长( wavelength的名词复数 )；具有相同的/不同的思路；合拍；不合拍

参考例句：

• I find him difficult to talk to—we're on completely different wavelengths. 我没法和他谈话，因为我们俩完全不对路。 来自《简明英汉词典》
• Sunlight consists of different wavelengths of radiation. 阳光由几种不同波长的射线组成。 来自辞典例句

5 spectrum   

n.谱，光谱，频谱；范围，幅度，系列

参考例句：

• This is a kind of atomic spectrum.这是一种原子光谱。
• We have known much of the constitution of the solar spectrum.关于太阳光谱的构成，我们已了解不少。

6 popcorn   

n.爆米花

参考例句：

• I like to eat popcorn when I am watching TV play at home.当我在家观看电视剧时，喜欢吃爆米花。
• He still stood behind his cash register stuffing his mouth with popcorn.他仍站在收银机后，嘴里塞满了爆米花。

7 neutron   

n.中子

参考例句：

• Neutron is neutral and slightly heavier than the proton.中子是中性的，比质子略重。
• Based on the neutron energy,the value of weighting factor was given.根据中子能量给出了相应的辐射权重因子的数值。

8 shred   

v.撕成碎片，变成碎片；n.碎布条，细片，些少

参考例句：

• There is not a shred of truth in what he says.他说的全是骗人的鬼话。
• The food processor can shred all kinds of vegetables.这架食品加工机可将各种蔬菜切丝切条。

9 shredding   

v.撕碎，切碎( shred的现在分词 )；用撕毁机撕毁（文件）

参考例句：

• Like the Tehran experience, the shredding may be all for naught. 如同德黑兰事件中的情况一样，切碎文件可能是徒劳的。 来自时文部分
• How shredding began is subject to some guesswork. 粉碎处理行业的起源是个有争议的问题。 来自时文部分

10 galaxy   

n.星系；银河系；一群(杰出或著名的人物)

参考例句：

• The earth is one of the planets in the Galaxy.地球是银河系中的星球之一。
• The company has a galaxy of talent.该公司拥有一批优秀的人才。

11 dense   

a.密集的，稠密的，浓密的；密度大的

参考例句：

• The general ambushed his troops in the dense woods. 将军把部队埋伏在浓密的树林里。
• The path was completely covered by the dense foliage. 小路被树叶厚厚地盖了一层。