我们现在有了有史以来最大的宇宙三维地图, thanks to a powerful instrument mounted atop a telescope in Arizona with a robotic array of 5,000只光纤“眼睛”可以看到夜空. 在过去的五年里, the Dark Energy Spectroscopic Instrument—known in science circles as DESI—has measured the spectra of more than 30 million galaxies and 3 million quasars to determine how fast the universe expanded over 11 billion years.
DESI今天的声明是一项持续的研究的结果 国际合作 由来自70多个机构的900多名研究人员组成, 包括正规欧洲杯买球网站圣克鲁兹分校的天文学家，他们在这个项目中担任领导角色.
然而，尽管这条新闻很重要，但他们说这只是个开始.
“If the trends hinted here in this first-year dataset are confirmed in our Year Three analysis, 这将是一个重大发现,宇宙学家Alexie Leauthaud说, 正规欧洲杯买球网站圣克鲁斯分校天文学和天体物理系副教授. “这将是一个非常激动人心的时刻，成为DESI合作的一部分.”
七月开始, Leauthaud will serve as a spokesperson for the effort—which entails lead-organizer duties—so she is perfectly positioned to provide updates. 正规欧洲杯买球网站圣克鲁斯分校的其他合作教授包括康妮·罗科西和J. Xavier Prochaska，也在天文学 & 天体物理学.
Rockosi led the commissioning of the instrument at the 4-meter Mayall telescope at Kitt Peak National Observatory, 她现在的角色是一名仪器科学家, 帮助它保持最佳状态. 除了, 教授们称赞正规欧洲杯买球网站圣克鲁斯分校的本科生是“一个非凡的团队”, 研究生, and postdocs who have been deeply engaged with the project—visiting the telescope in Arizona on a regular basis to help with observations.
正如在 公告 来自劳伦斯伯克利国家实验室, DESI的基础是:“理解我们的宇宙是如何进化的，与它是如何结束的, 以及物理学中最大的谜团之一:暗能量, 导致宇宙膨胀越来越快的未知成分.”
This is the first time scientists have measured the expansion history of the young universe with a precision better than 1%—giving us our best view yet of how the universe evolved. 研究人员分享了他们第一年收集数据的分析 多个文件 that will be posted today on the arXiv and in talks at the American Physical Society meeting in the United States and the Rencontres de Moriond in Italy.
斯文Heydenreich, 正规欧洲杯买球网站圣克鲁斯分校的博士后研究学者, 在DESI身兼数职:在一个面向早期职业科学家的委员会任职, 用仪器进行星系间的测量, and co-leading a working group that forecasts different scenarios for a potential continuation of the DESI mission.
“The goal is to measure how DESI galaxies bend and distort the light from more distant galaxies located behind them, 这种效应被称为引力透镜效应,海登赖希说, 谁在2023年底在基特峰呆了一周. “These measurements will be essential for analyzing how galaxies are influenced by the distribution of dark matter surrounding them. 此外, the results will help improve our understanding of the parameters that describe our current model of the universe's composition and evolution.”
一个11吨重的时间机器
DESI的组件被设计成自动指向预先选定的星系群, 收集他们的光, and then split that light into narrow bands of color to precisely map their distance from Earth and gauge how much the universe expanded as this light traveled to Earth. 在理想条件下，DESI可以每20分钟循环一次新的5000个星系.
By repeatedly mapping the distance to the many millions of galaxies and quasars across one-third of the area of the sky over the past five years, DESI教给我们更多关于暗能量和宇宙历史的知识. 我们目前的理解是，引力减缓了早期宇宙的膨胀速度, 但是暗能量加速了它的膨胀.
DESI对整个110亿年膨胀历史的总体精度为0.5%, and the most distant epoch—covering 8-11 billion years in the past—has a record-setting precision of 0.82%. 对我们年轻的宇宙进行测量是非常困难的. 然而在一年之内, DESI has become twice as powerful at measuring the expansion history at these early times as its predecessor (the Sloan Digital Sky Survey’s BOSS/eBOSS), 这花了十多年时间.
看看DESI的地图, it’s easy to see the underlying structure of the universe: strands of galaxies clustered together, 被空洞隔开，物体更少. 我们早期的宇宙, 远远超出了DESI的观点, 完全不同:热, dense soup of subatomic particles moving too fast to form stable matter like the atoms we know today. 这些粒子中有氢核和氦核，统称为重子.
这种早期电离等离子体的微小波动引起了压力波, moving the baryons into a pattern of ripples that is similar to what you’d see if you tossed a handful of gravel into a pond. 随着宇宙膨胀和冷却, 中性原子形成，压力波停止, freezing the ripples in three dimensions and increasing clustering of future galaxies in the dense areas. 数十亿年后, 我们仍然可以看到这种微弱的三维涟漪, 或泡沫, in the characteristic separation of galaxies—a feature called 重子声学振荡 (BAOs).
研究人员使用BAO测量作为宇宙的标尺. 通过测量这些气泡的表观大小, they can determine distances to the matter responsible for this extremely faint pattern on the sky. 绘制BAO气泡的近处和远处的地图可以让研究人员将数据分割成块, measuring how fast the universe was expanding at each time in its past and modeling how dark energy affects that expansion.
“We’ve measured the expansion history over this huge range of cosmic time with a precision that surpasses all of the previous BAO surveys combined,徐熙钟说, 他是俄亥俄大学教授，也是DESI BAO分析的联合负责人. “We're very excited to learn how these new measurements will improve and alter our understanding of the cosmos. 人类对宇宙有着永恒的迷恋, 想知道它是由什么构成的，又想知道它会发生什么.”
DESI is supported by the DOE Office of Science and by the National Energy 研究 Scientific Computing Center, 美国能源部科学办公室的用户设施. 对DESI的额外支持是由美国国防部提供的.S. National Science Foundation; the Science and Technology Facilities Council of the United Kingdom; the Gordon and Betty Moore Foundation; the Heising-Simons Foundation; the French Alternative Energies and Atomic Energy Commission (CEA); the National Council of Humanities, 科学, and Technologies of Mexico; the Ministry of Science and Innovation of Spain; and by the DESI member institutions.
The DESI collaboration is honored to be permitted to conduct scientific research on Iolkam Du’ag (Kitt Peak), 这座山对托霍诺奥哈姆民族有着特殊的意义.
