VOA科学技术2023--A New Way to Look at the Milky Way

A New Way to Look at the Milky¹ Way

For many years, humans have looked up at the collection of stars and planets shining in the night sky that make up the Milky Way. However, the Milky Way is now being observed for the first time in a new way.

Scientists said recently that they have produced an image of the Milky Way not based on light. Instead, the image is based on subatomic particles called neutrinos.

Scientists discovered the high-energy neutrinos in ice deep below Antarctica's surface. They then traced their source back to locations in the Milky Way. It is the first time these particles have been observed arising from our galaxy².

This observation of the galaxy is different from what can be seen with our own eyes, or even instruments that measure other electromagnetic sources like radio waves, microwaves, or X-rays.

The image does not contain stars or planets or other things observable because of their light. Rather they are observable because of the neutrinos originating in the galaxy. The neutrinos may be from explosive star deaths called supernovas.

The neutrinos were discovered over a period of 10 years at the IceCube Neutrino Observatory³. It is part of a U.S. scientific research station at the South Pole. The researchers used more than 5,000 sensors⁴ covering an area the size of a small mountain.

"This observation is groundbreaking. It established the galaxy as a neutrino source. Every future work will refer to this observation," said Georgia Tech physicist⁵ Ignacio Taboada. He is the spokesperson for the IceCube research.

Neutrinos are electrically neutral. They are not affected⁶ by even the strongest magnetic field and rarely interact with matter. That is why they are also called the "ghost particle." As neutrinos travel through space, they pass clear through matter like stars, planets, and even people.

"Just as light goes without stopping through glass, neutrinos can go through everything, including the whole planet Earth," Taboada said.

Naoko Kurahashi Neilson is a physicist at Drexel University in Philadelphia. She is a member of the research team that published its findings in the publication Science. Neilson said neutrinos are elementary particles, meaning they are not made up of anything smaller.

"They are not the building blocks of stuff, like electrons and quarks are, but they are created in nuclear processes," she said.

Many parts of the universe are impossible to observe using light alone. The ability to use particles like neutrinos in astronomy makes for a more complete examination.

Neutrinos are produced by the same sources as cosmic rays, the highest-energy particles ever observed. But cosmic rays, as electrically charged particles, cannot be traced directly back to their source. Strong magnetic fields in space change their path. But the direction from which neutrinos arrive points directly to their original source.

The researchers used machine learning to help determine which neutrinos originated in our galaxy and which originated elsewhere.

How the neutrinos originated is up for debate.

"This is now the key question," said IceCube lead scientist Francis Halzen. "Neutrinos only originate in sources where cosmic rays are produced ...The key question is where these cosmic rays originate," Halzen said.

"The most likely source of neutrinos and cosmic rays in our galaxy, are the remains⁷ of past supernova explosions," Taboada added. "But this is unproven so far."

Words in This Story

trace — v. to follow the path or line of

source — n. the cause of something

galaxy — n. any one of the very large groups of stars that make up the universe

originate — v. to begin to exist

groundbreaking — adj. introducing new ideas or methods

neutral — adj. not having an electrical charge

stuff — n. a group or pile of things that are not specifically described

quark — n. any one of several types of very small particles that make up matter

key — adj. extremely important

1 milky   

adj.牛奶的，多奶的；乳白色的

参考例句：

• Alexander always has milky coffee at lunchtime.亚历山大总是在午餐时喝掺奶的咖啡。
• I like a hot milky drink at bedtime.我喜欢睡前喝杯热奶饮料。

2 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。

3 observatory   

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。

4 sensors   

n.传感器，灵敏元件( sensor的名词复数 )

参考例句：

• There were more than 2000 sensors here. 这里装有两千多个灵敏元件。 来自《简明英汉词典》
• Significant changes have been noted where sensors were exposed to trichloride. 当传感器暴露在三氯化物中时，有很大变化。 来自辞典例句

5 physicist   

n.物理学家，研究物理学的人

参考例句：

• He is a physicist of the first rank.他是一流的物理学家。
• The successful physicist never puts on airs.这位卓有成就的物理学家从不摆架子。

6 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。

7 remains   

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。