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Scientists Find Evidence of Oldest Dark Matter in Universe

时间:2022-08-29 08:51:53

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Scientists Find Evidence of Oldest Dark Matter in Universe

Researchers say they have discovered evidence of the oldest dark matter ever observed in the universe.

Dark matter remains1 mysterious. Scientists believe the material makes up more than one quarter of the universe. But it cannot be directly seen or felt.

Astronomers2 have theorized that dark matter exists because of gravity's observed effects on galaxies3. They believe dark matter provides a kind of protective barrier that prevents galaxies from coming apart.

Scientists report in a new study that they used satellite and telescope equipment to collect data that led them to observe dark matter as it existed 12 billion years ago. That is not long after the Big Bang, which is believed to have happened about 13.8 billion years ago. The Big Bang is the explosion that many scientists believe created the universe.

The research team was led by scientists from Japan's Nagoya University. It also included researchers from the University of Tokyo, the National Astronomical4 Observatory5 of Japan and America's Princeton University.

When spacecraft, telescopes and other equipment observe distant galaxies, they are seeing them as they existed in the past. This is because of the amount of time it takes for light to travel. So in some cases, the observations involve events that happened millions or billions of years ago.

Since dark matter does not give off light, it is very difficult to observe. To do so, scientists look at how the material reacts to gravitational forces.

One method for this is called gravitational lensing. This involves observing how the gravity of large collections of galaxies bend and distort the light of more distant galaxies that sit behind the galaxy6 group, the American space agency NASA explains.

While gravitational lensing is one way to measure amounts of dark matter, the method is more difficult when trying to observe the material in the most distant parts of the universe. The farther the galaxy, the more difficult it is to observe bending and distortion of light.

So the researchers involved in the new study used another method to observe distant dark matter. They decided7 to use a different source for background light. This source is known as the Cosmic Microwave Background (CMB). The CMB is leftover8 radiation from the Big Bang and serves as the main source of information about the early universe.

The team first used data from observations made by an instrument called the Subaru Hyper Suprime-Cam Survey, which operates at the Subaru Telescope in Hawaii. With this data, the researchers said they were able to identify 1.5 million galaxies seen by faintly observed light from 12 billion years ago.

Then, the scientists used another method to search for dark matter even further away. They used cosmic microwaves observed by the European Space Agency's Plank9 satellite to measure how dark matter around distant galaxies distorted the microwaves.

Yuichi Harikane is an assistant professor at the University of Tokyo's Institute for Cosmic Ray Research. He helped lead the research, recently published in Physical Review Letters.

"Most researchers use background source galaxies to measure dark matter distribution from the present to eight billion years ago," Harikane said in a statement. He added that using the more distant CMB as a background source made the new dark matter discovery possible. "For the first time, we were measuring dark matter from almost the earliest moments of the universe."

University of Tokyo professor Masami Ouchi led many of the new observations. He said that the idea to look for dark matter in distant galaxies was completely new before the team began the project. "Look at dark matter around distant galaxies? It was a crazy idea. No one realized we could do this," Ouchi said.

Nagoya University professor Hironao Miyatake said he was happy the researchers were able to "open a new window" into such a distant time. "Twelve billion years ago, things were very different. You see more galaxies that are in the process of formation than at the present. The first galaxy clusters are starting to form as well," Miyatake said.

Words in This Story

bend – v. to become curved, or to make something become curved

distort – v. to change the shape, sound or appearance of something

source – n. the place where something comes from or starts at

faint – adj. not strong or clear

distribute – v. to give out or spread something

cluster – n. a collection of stars or galaxies that appear close together in the sky and are gravitationally linked.


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1 remains 1kMzTy     
n.剩余物,残留物;遗体,遗迹
参考例句:
  • He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
  • The remains of the meal were fed to the dog.残羹剩饭喂狗了。
2 astronomers 569155f16962e086bd7de77deceefcbd     
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 fa8833b92b82bcb88ee3b3d7644caf77     
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 astronomical keTyO     
adj.天文学的,(数字)极大的
参考例句:
  • He was an expert on ancient Chinese astronomical literature.他是研究中国古代天文学文献的专家。
  • Houses in the village are selling for astronomical prices.乡村的房价正在飙升。
5 observatory hRgzP     
n.天文台,气象台,瞭望台,观测台
参考例句:
  • Guy's house was close to the observatory.盖伊的房子离天文台很近。
  • Officials from Greenwich Observatory have the clock checked twice a day.格林威治天文台的职员们每天对大钟检查两次。
6 galaxy OhoxB     
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。
7 decided lvqzZd     
adj.决定了的,坚决的;明显的,明确的
参考例句:
  • This gave them a decided advantage over their opponents.这使他们比对手具有明显的优势。
  • There is a decided difference between British and Chinese way of greeting.英国人和中国人打招呼的方式有很明显的区别。
8 leftover V97zC     
n.剩货,残留物,剩饭;adj.残余的
参考例句:
  • These narrow roads are a leftover from the days of horse-drawn carriages.这些小道是从马车时代沿用下来的。
  • Wonder if that bakery lets us take leftover home.不知道那家糕饼店会不会让我们把卖剩的带回家。
9 plank p2CzA     
n.板条,木板,政策要点,政纲条目
参考例句:
  • The plank was set against the wall.木板靠着墙壁。
  • They intend to win the next election on the plank of developing trade.他们想以发展贸易的纲领来赢得下次选举。

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