网易科技讯10月10日动静，据《新科学家》报道，科学家终究发觉星系取星系之间起到毗连的物质。此次发觉意义严沉，由于这是我们第一次发觉了占中大约一半的一般物质，而之前对恒星、星系和太空中其他敞亮物体的不雅测存正在的疑虑获得领会释。
计较机模仿呈现出一大块“网”，从这张图中我们能够看到纠缠的丝状物将的星系毗连正在一,而这种纠缠状物就是由沉子构成的。
沉子是由三夸克构成的亚原子粒子。正在现代粒子物理学的尺度模子理论中，沉子这一名词是指由三个夸克（或者三个反夸克构成反沉子）构成的复合粒子。正在这理论中它是强子的一类。值得留意的是，由于沉子属于复合粒子，所以不是根基粒子。最常见的沉子有构成日常物质原子核的质子和中子，取反质子、反中子合称为核子。此前天文学家发觉了很多缕高温、呈散射状的“气体”，恰是这些“气体”将的星系毗连正在一，可是他们并不晓得这些“气体”中有什么物质，而现正在的发觉处理了天文学家的。
由于这些呈丝状的“气体”温度虽高还不敷高，因而不会出太多的能量，所以用X射线千里镜很难不雅测到这些物质。可是研究人员通过一种被称为“活动学SZ（sunyaev-zeldovich）效应”的现象证明了这些物质的存正在，这种效应描述了从大爆炸中遗留下来的光穿过热气体时形态。
你大概传闻过暗物质的搜索，所谓暗物质，是一种被认为正在中洋溢的奥秘物质，而我们能够通过引力来间接不雅测到这种奥秘物质发生的影响。做个抽象的注释，好比说按照目前所察看到的，某处有1个单元的通俗物质，可是我们此次计较机模仿的模子却不雅测到了2个单元的通俗物质，因而这多出的一倍“消逝的物质”就是研究发觉的环节。
两个的研究小组发觉的“消逝的物质”——由称为沉子的粒子形成的，并不是暗物质。毗连星系的丝状物弥散气体就是由沉子构成的。法国空间物理学研究所Hideki Tanimura的团队堆叠了260000个双星系数据，英国大学的Anna de Graaff的研究小组利用跨越一百万双星系数据。两队发觉了确凿的证明星系之间的气体细丝。Tanimura的团队发觉气体细丝几乎是预测的一般物质的三倍密度，Graaff的团队发觉是六倍一般物质密度——证明了这些区域的气体脚够浓密构成细丝。
“明显我们两个团队的不雅测存正在差别，这一点我们正在不雅测前就料想到了，由于我们不雅测的距离分歧，所以形成告终果上的分歧，”Tanimura说。“若是降服这个要素，我们的不雅测会和另一小组很是分歧。”
两个团队都从斯隆数字巡天项目选择了双星系进行研究，双星系被认为是由沉子链毗连。他们堆叠两星系区域之间的普朗克信号，使得微弱的沉子链可探测到。
“每小我都晓得它的存正在，但现正在，我们两个分歧的团队明白的发觉了这种物质，”州哈佛史密森物理学核心的拉尔夫·克拉夫特说道，“沉子的不雅测很好地证了然我们关于我们关于星系若何构成以及的汗青等很多概念都是准确的。”
2015年，普朗克卫星正在可不雅测微波辐射布景地图。由于星系之间气体如斯弥散，他们形成的暗黑点太弱以致于正在普朗克地图上不克不及间接看到。
以下为《新科学家》原文：
Half the universe’s missing matter has just been finally found
Discoveries seem to back up many of our ideas about how the universe got its large-scale structure
Andrey Kravtsov (The University of Chicago) and Anatoly Klypin (New Mexico State University). Visualisation by Andrey Kravtsov
By Leah Crane
The missing links between galaxies have finally been found. This is the first detection of the roughly half of the normal matter in our universe – protons, neutrons and electrons – unaccounted for by previous observations of stars, galaxies and other bright objects in space.
You have probably heard about the hunt for dark matter, a mysterious substance thought to permeate the universe, the effects of which we can see through its gravitational pull. But our models of the universe also say there should be about twice as much ordinary matter out there, compared with what we have observed so r.
Two separate teams found the missing matter – made of particles called baryons rather than dark matter – linking galaxies together through filaments of hot, diffuse gas.
“The missing baryon problem is solved,” says Hideki Tanimura at the Institute of Space Astrophysics in Orsay, France, leader of one of the groups. The other team was led by Anna de Graaff at the University of Edinburgh, UK.
Because the gas is so tenuous and not quite hot enough for X-ray telescopes to pick up, nobody had been able to see it before.
“There’s no sweet spot – no sweet instrument that we’ve invented yet that can directly observe this gas,” says Richard Ellis at University College London. “It’s been purely speculation until now.”
So the two groups had to find another way to definitively show that these threads of gas are really there.
Both teams took advantage of a phenomenon called the Sunyaev-Zel’dovich effect that occurs when light left over from the big bang passes through hot gas. As the light travels, some of it scatters off the electrons in the gas, leaving a dim patch in the cosmic microwave background – our snapshot of the remnants from the birth of the cosmos.
Stack ‘em up
In 2015, the Planck satellite created a map of this effect throughout the observable universe. Because the tendrils of gas between galaxies are so diffuse, the dim blotches they cause are r too slight to be seen directly on Planck’s map.
Both teams selected pairs of galaxies from the Sloan Digital Sky Survey that were expected to be connected by a strand of baryons. They stacked the Planck signals for the areas between the galaxies, the individually int strands detectable en masse.
Tanimura’s team stacked data on 260,000 pairs of galaxies, and de Graaff’s group used over a million pairs. Both teams found definitive evidence of gas filaments between the galaxies. Tanimura’s group found they were almost three times denser than the mean for normal matter in the universe, and de Graaf’s group found they were six times denser – confirmation that the gas in these areas is dense enough to form filaments.
“We expect some differences because we are looking at filaments at different distances,” says Tanimura. “If this ctor is included, our findings are very consistent with the other group.”
Finally finding the extra baryons that have been predicted by decades of simulations validates some of our assumptions about the universe.
“Everybody sort of knows that it has to be there, but this is the first time that somebody – two different groups, no less – has come up with a definitive detection,” says Ralph Kraft at the Harvard-Smithsonian Center for Astrophysics in Massachusetts.
“This goes a long way toward showing that many of our ideas of how galaxies form and how structures form over the history of the universe are pretty much correct,” he says.
Journal references: arXiv, 1709.05024 and 1709.10378v1