天文3d和物理学院的scottcroom教授领导的研究已经排除了质量和环境因素是星系混沌增加的主要驱动因素。 来自3000多个星系的数据表明，正是年龄导致了星系结构的相对无序。 三井星系调查队观测到的3000多个星系中的一个，由三井望远镜拍摄的图像。 信用：hsc ssp/m。 koike/naoj星系的恒星以有序的模式旋转开始生命，但在某些星系中，恒星的运动更为随机。 到目前为止，科学家们一直不确定是什么导致了这种情况——可能是周围的环境或星系本身的质量。 发表在英国皇家天文学会月报上的一项新研究报告称，最重要的因素不是这两件事。 这表明恒星随机运动的趋势主要是由星系的年龄驱动的&随着时间的推移，事情会变得一团糟。 这项研究的主要作者是来自物理学院、arcastro3d和悉尼天文研究所的scottcroom教授。 他说：“当我们进行分析时，我们发现年龄始终是最重要的参数。 一旦考虑到年龄，基本上就没有环境趋势，而质量也是如此。 “如果你发现一个年轻的星系，无论它在什么环境中，它都会旋转；如果你发现了一个古老的星系，它的轨道会更随机，无论它是在稠密的环境中还是在空洞中。 “更新星系知识”这项研究更新了我们对先前研究的理解，这些研究不同地认为环境或质量是更重要的因素。 但第二作者jesse van de sande博士说，早期的研究并不一定是错误的。 年轻的星系是恒星形成的超级工厂，而在较老的星系中，恒星形成停止了。 “我们知道年龄是受环境影响的。 如果一个星系落入稠密的环境中，它将倾向于关闭恒星的形成。 因此，在密度更大的环境中的星系平均来说更古老，”范德桑德博士说。 “我们分析的重点是，并不是生活在密集的环境中会减少它们的自转，而是它们更老了。 “我们自己的银河系，银河系，仍然有一个薄的恒星形成盘，所以仍然被认为是一个高自旋旋转星系。 克罗姆教授说：“但当我们详细观察银河系时，我们确实看到了一种叫做银河厚盘的东西。 就光而言，它并不占主导地位，但它确实存在，而且这些恒星看起来都是较老的恒星，它们很可能在更早的时候被薄圆盘加热，或者在早期宇宙中伴随着更多的湍流运动而诞生。 萨米星系调查这项研究使用了萨米星系调查的观测数据。 sami仪器由悉尼大学和英澳天文台（现为astralis）于2012年建造。 萨米在新南威尔士州库纳巴拉布兰附近的西丁斯普林天文台使用英澳望远镜。 它已经调查了3000个星系，分布在各种各样的环境中。 作为萨米星系调查的一部分，年轻（顶部）和年老（底部）星系的比较，包括旋转速度（中心）和随机速度（右）。 顶部星系的平均年龄为20亿年，自转速度快，随机运动少。 底部星系的平均年龄为12岁。 50亿年，较慢的自转和更大的随机运动。 这项研究使天文学家在试图了解星系形成和微调宇宙发展模型时，能够排除许多过程。 下一步将是开发更精细的星系演化模拟。 “正确进行模拟的挑战之一是预测发生了什么需要高分辨率。 克罗姆教授说：“目前典型的模拟是基于质量约为10万颗恒星的粒子，而你无法分辨星系盘中的小规模结构。”。 赫克托星系调查将帮助克罗姆教授和他的团队使用英澳望远镜上的一种新仪器来扩大这项工作。 julia bryant教授在萨米测量望远镜内。 照片：scottcroom悉尼大学hector星系调查负责人juliabryant教授说：“hector正在观测15000个星系，但具有更高的光谱分辨率，即使在质量低得多的星系中也可以测量星系的年龄和自转，并提供更详细的环境信息。”。 astro3d的主任emmarryanweber教授说：“这些发现回答了astro3d提出的一个关键问题：质量和角动量是如何在宇宙中演化的？sami团队的这项细致研究揭示了星系的年龄决定了恒星的轨道。”。 这一关键信息有助于更清晰地了解宇宙的全貌。 研究小组还包括来自麦考瑞大学、斯温本理工大学、西澳大利亚大学、澳大利亚国立大学、新南威尔士大学、剑桥大学、昆士兰大学和韩国延世大学的科学家。 萨米星系巡天正在运行声明作者声明没有相互竞争的利益。 这项研究由澳大利亚研究委员会资助。research led by professor scott croom from astro 3d and the school of physics has ruled out mass and environmental factors as the main drivers of increasing galactic chaos. data from more than 3000 galaxies has shown it is age that leads to relative disorganisation in galactic structure.an image taken by the subaru telescope of one of more than 3000 galaxies observed by the sami galaxy survey team. credit: hsc-ssp/m. koike/naojgalaxies start life with their stars rotating in an orderly pattern but in some the motion of stars is more random. until now, scientists have been uncertain about what causes this – possibly the surrounding environment or the mass of the galaxy itself.a new study, published in the monthly notices of the royal astronomical society, has reported that the most important factor is neither of these things. it shows the tendency of the stars to have random motion is driven mostly by the age of the galaxy – things just get messy over time.the study’s lead author is professor scott croom from the school of physics, arc astro 3d and sydney institute for astronomy.he said: “when we did the analysis, we found that age, consistently, whichever way we slice or dice it, is always the most important parameter. once you account for age, there is essentially no environmental trend, and it’s similar for mass.“if you find a young galaxy it will be rotating, whatever environment it is in, and if you find an old galaxy, it will have more random orbits, whether it’s in a dense environment or a void.”updating galactic knowledgethe study updates our understanding from previous studies that have variously suggested environment or mass as more important factors. but the earlier work is not necessarily incorrect, said second author dr jesse van de sande.young galaxies are star-forming super-factories, while in older ones, star formation ceases.“we do know that age is affected by environment. if a galaxy falls into a dense environment, it will tend to shut down the star formation. so, galaxies in denser environments are, on average, older,” dr van de sande said.“the point of our analysis is that it’s not living in dense environments that reduces their spin, it’s the fact that they’re older.”our own galaxy, the milky way, still has a thin star forming disk, so is still considered a high spin rotational galaxy.professor croom said: “but when we look at the milky way in detail, we do see something called the milky way thick disk. it’s not dominant, in terms of light, but it is there and those look to be older stars, which may well have been heated from the thin disk at earlier times, or born with more turbulent motion in the early universe.”sami galaxy surveythe research used data from observations made under the sami galaxy survey. the sami instrument was built in 2012 by the university of sydney and the anglo-australian observatory (now astralis). sami uses the anglo-australian telescope, at siding spring observatory, near coonabarabran, new south wales. it has surveyed 3000 galaxies across a large range of environments.a comparison of a young (top) and old (bottom) galaxy observed as part of the sami galaxy survey, including rotational velocity (centre) and random velocities (right). the top galaxy has an average age of 2 billion years, high rotation and low random motion. the bottom galaxy has an average age of 12.5 billion years, slower rotation and much larger random motion. image from the hyper suprime-cam subaru strategic programthe study allows astronomers to rule out many processes when trying to understand galaxy formation and fine-tune models of how the universe has developed. the next steps will be to develop simulations of galaxy evolution with more granular detail.“one of the challenges of getting simulations right is the high resolution you need to predict whats going on. typical current simulations are based on particles which have the mass of maybe 100,000 stars and you cant resolve small-scale structures in galaxy disks,” professor croom said.the hector galaxy survey will help professor croom and his team expand this work using a new instrument on the anglo-australian telescope.professor julia bryant inside the sami survey telescope. photo: scott croom“hector is observing 15,000 galaxies but with higher spectral resolution, allowing the age and spin of galaxies to be measured even in much lower mass galaxies and with more detailed environmental information,” said professor julia bryant, lead of the hector galaxy survey at the university of sydney.professor emma ryan-weber, director of astro 3d, said: “these findings answer one of the key questions posed by astro 3d: how does mass and angular momentum evolve in the universe? this careful work by the sami team reveals that the age of a galaxy determines how the stars orbit. this critical piece of information contributes to a clearer big-picture view of the universe.”the research team also included scientists from macquarie university, swinburne university of technology, the university of western australia, the australian national university, the university of new south wales, the university of cambridge, the university of queensland, and yonsei university in the republic of korea.sami galaxy survey in operationdeclarationthe authors declare no competing interests. research was funded by the australian research council.本文来源： 星系随着年龄的增长变得更加混乱
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