用图搬运：NASA对暗物质的解释

ASUKI

摘自NASA[1]。
一、为什么要假设暗物质：

By measuring the motions of stars and gas, astronomers can "weigh" galaxies. In our own solar system, we can use the velocity of the Earth around the Sun to measure the Sun's mass. The Earth moves around the Sun at 30 kilometers per second (roughly sixty thousand miles per hour). If the Sun were four times more massive, then the Earth would need to move around the Sun at 60 kilometers per second in order for it to stay on its orbit. The Sun moves around the Milky Way at 225 kilometers per second. We can use this velocity (and the velocity of other stars) to measure the mass of our Galaxy. Similarly, radio and optical observations of gas and stars in distant galaxies enable astronomers to determine the distribution of mass in these systems.

翻译：通过测量恒星和气体的运动，天文学家可以“称量”星系。 在我们自己的太阳系中，我们可以利用地球绕太阳的速度来测量太阳的质量。 地球以每秒30公里（每小时约6万英里）的速度绕太阳运动。 如果太阳的质量大四倍，那么地球将需要以每秒60公里的速度绕太阳运动，以使其保持在轨道上。 太阳以每秒225公里的速度绕银河运动。 我们可以使用该速度（以及其他恒星的速度）来测量银河系的质量。 同样，对遥远星系中气体和恒星的无线电和光学观测，使天文学家能够确定这些系统中质量的分布。
图片翻译：

The mass that astronomers infer for galaxies, including our own, is roughly ten times larger than the mass that can be associated with stars, gas and dust in a Galaxy. This mass discrepancy has been confirmed by observations of gravitational lensing, the bending of light predicted by Einstein's theory of general relativity.
By measuring how the background galaxies are distorted by the foreground cluster, astronomers can measure the mass in the cluster. The mass in the cluster is more than five times larger than the inferred mass in visible stars, gas and dust.

翻译：天文学家推断出包括我们自己在内的星系的质量，大约是星系中与恒星，气体和尘埃有关的质量的十倍。 这种质量差异已通过对引力透镜的观察得以证实，这是爱因斯坦的广义相对论所预测的光的弯曲。
通过测量背景星团是如何扭曲背景星系的，天文学家可以测量星团中的质量。 星团中的质量比可见恒星，气体和尘埃中推断的质量大五倍以上。
图片翻译：
引力透镜效应
讨论：为什么银河系的实际质量要比银河系中的物质的质量和大呢？
于是科学家引入了暗物质，来把这缺少的质量给补上。
二、暗物质的是什么？

What is the nature of the "dark matter", this mysterious material that exerts a gravitational pull, but does not emit nor absorb light? Astronomers do not know.
There are a number of plausible speculations on the nature of the dark matter:

翻译：“暗物质”的本质是什么？这种神秘的物质会施加引力，但不发光也不吸收光？ 天文学家不知道其原因。
关于暗物质的性质有许多合理的推测：

Brown Dwarfs: if a star's mass is less than one twentieth of our Sun, its core is not hot enough to burn either hydrogen or deuterium, so it shines only by virtue of its gravitational contraction. These dim objects, intermediate between stars and planets, are not luminous enough to be directly detectable by our telescopes. Brown Dwarfs and similar objects have been nicknamed MACHOs (MAssive Compact Halo Objects) by astronomers. These MACHOs are potentially detectable by gravitational lensing experiments. If the dark matter is made mostly of MACHOs, then it is likely that baryonic matter does make up most of the mass of the universe.

翻译：布朗矮星：如果一颗恒星的质量小于我们太阳的二十分之一，那么它的核心温度还不够高，无法燃烧氢或氘，因此仅依靠重力收缩就可以发光。 这些介于恒星和行星之间的昏暗物体的发光强度不足以被我们的望远镜直接检测到。 天文学家将棕矮星和类似物体称为MACHO（大型紧凑光环物体）。 这些MACHOs可以通过引力透镜实验检测到。 如果暗物质主要由MACHO组成，那么重子物质很可能构成了宇宙的大部分。
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Supermassive Black Holes: these are thought to power distant "K" type quasars. Some astronomers speculate that dark matter may be made up of copious numbers of black holes. These black holes are also potentially detectable through their lensing effects.

翻译：超大质量黑洞：这些被认为可以为遥远的“ K”型类星体提供动力。 一些天文学家推测，暗物质可能是由大量的黑洞组成的。 这些黑洞还可以通过其透镜效应来检测。
图片翻译：

New forms of matter: particle physicists, scientists who work to understand the fundamental forces of nature and the composition of matter, have speculated that there are new forces and new types of particles. One of the primary motivations for building "supercolliders" is to try to produce this matter in the laboratory. Since the universe was very dense and hot in the early moments following the Big Bang, the universe itself was a wonderful particle accelerator. Cosmologists speculate that the dark matter may be made of particles produced shortly after the Big Bang. These particles would be very different from ordinary "baryonic matter". Cosmologists call these hypothetical particles WIMPs (for Weakly Interacting Massive Particles) or "non-baryonic matter".

翻译：物质的新形式：粒子物理学家，致力于理解自然的基本力和物质组成的科学家，推测存在着新的力量和新型的粒子。 建立“超级对撞机”的主要动机之一是试图在实验室中制造这种物质。 由于宇宙在大爆炸之后的初期非常茂密和炎热，因此宇宙本身就是一个极好的粒子加速器。 宇宙学家推测，暗物质可能是由大爆炸之后不久产生的颗粒组成的。 这些粒子将与普通的“重子物质”有很大的不同。 宇宙学家称这些假设的粒子为WIMP（弱相互作用的大质量粒子）或“非重子物质”。
图片翻译：
三、补充

暗物质和暗能量在宇宙中的占比：
翻译：原子4.6%，暗物质24%，暗能量71.4%
我就是一个没有感情的搬运工，我什么都不知道。
参考

• ^https://map.gsfc.nasa.gov/universe/uni_matter.html
  

作者：一点资讯