Molecular clouds in the Cosmic Snake normal star-forming galaxy 8 billion years ago
Miroslava Dessauges-Zavadsky, Johan Richard, Françoise Combes, Daniel Schaerer, Wiphu Rujopakarn, Lucio Mayer, Antonio Cava, Frédéric Boone, Eiichi Egami, Jean-… 展开作者
Miroslava Dessauges-Zavadsky, Johan Richard, Françoise Combes, Daniel Schaerer, Wiphu Rujopakarn, Lucio Mayer, Antonio Cava, Frédéric Boone, Eiichi Egami, Jean-Paul Kneib, Pablo G. Pérez-González, Daniel Pfenniger, Tim D. Rawle, Romain Teyssier, Paul P. van der Werf
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1 pages, 4 figures, Supplementary information containing 8 figures and 1 table, published in Nature Astronomy
The cold molecular gas in contemporary galaxies is structured in discrete cloud complexes. These giant molecular clouds (GMCs), with $10^4$-$10^7$ solar masses and radii of 5-100 parsecs, are the seeds of star formation. Highlighting the molecular gas structure at such small scales in distant galaxies is observationally challenging. Only a handful of molecular clouds were reported in two extreme submillimetre galaxies at high redshift. Here we search for GMCs in a typical Milky Way progenitor at z = 1.036. Using the Atacama Large Millimeter/submillimeter Array (ALMA), we mapped the CO(4-3) emission of this gravitationally lensed galaxy at high resolution, reading down to 30 parsecs, which is comparable to the resolution of CO observations of nearby galaxies. We identify 17 molecular clouds, characterized by masses, surface densities and supersonic turbulence all of which are 10-100 times higher than present-day analogues. These properties question the universality of GMCs and suggest that GMCs inherit their properties from ambient interstellar medium. The measured cloud gas masses are similar to the masses of stellar clumps seen in the galaxy in comparable numbers. This corroborates the formation of molecular clouds by fragmentation of distant turbulent galactic gas disks, which then turn into stellar clumps ubiquitously observed in galaxies at cosmic noon.
The Andromeda galaxy's most important merger about 2 billion years ago as M32's likely progenitor
虽然仙女座星系（M31）的邻近提供了一个了解合并如何影响星系的机会，但关于M31最重要的合并仍然存在不确定性。先前的研究分别集中在巨大的恒星流或M32对M31盘的影响上，从而提出了许多重要的卫星相互作用。然而，M31的盘面加热模型和M31外围不同潮汐子结构的恒星星族之间的相似性都表明了一个单一的大合并。M31的恒星晕（其外部低表面亮度区域）是由卫星的潮汐碎片形成的，并提供了有关其重要合并的信息。在这里，我们使用星系形成的宇宙学模型来证明，M31的大质量和富含金属的恒星晕，包含了中等年龄的恒星，大大缩小了允许相互作用的范围，需要一个单一的主导合并与一个大星系（恒星质量约为2.5 x 10^10太阳质量，本星系群的第三大成员）约2 Gyr前。这个单一的事件解释了许多以前被单独考虑的观测结果：M31的致密且富含金属的卫星M32可能是分裂星系的剥离核心，其旋转的内部恒星晕包含了大部分合并碎片，巨大的恒星流可能是在合并过程中被抛出的。这种相互作用可以解释M31在大约2 Gyr前的恒星形成的全球爆发，其中大约五分之一的恒星形成。此外，M31的盘和凸起已经就位，这表明这种规模的合并不需要对星系结构产生显着影响。
Bar-driven secular evolution largely complete in a disk galaxy 7.6 billion years ago
Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo（东京大学宇宙粒子天体物理研究所）；Astronomical Institute, Tohoku University（东北大学天文研究所）；Department of Astronomy, School of Physics, Peking University（北京大学物理学院天文学系）；Kavli Institute for Astronomy and Astrophysics, Peking University（北京大学科维理天文与天体物理研究所）；Research School of Astronomy and Astrophysics, Australian National University（澳大利亚国立大学天文与天体物理研究学院）；Sydney Institute for Astronomy, The University of Sydney（悉尼大学悉尼天文研究所）；Graduate Institute for Advanced Studies (SOKENDAI)（综合研究大学院大学）；National Astronomical Observatory of Japan, National Institutes of Natural Sciences（日本国立自然科学研究所国立天文台）；Centre for Astrophysics and Supercomputing, Swinburne University of Technology（斯威本科技大学天体物理与超级计算中心）
Evidence of a massive accretion event 1.8 billion years before the Gaia-Sausage-Enceladus merger
Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, INAF（博洛尼亚天文与空间科学观测站，意大利国家天体物理研究所）；Dipartimento di Fisica e Astronomia, Università degli Studi di Bologna（博洛尼亚大学物理与天文系）；Kapteyn Astronomical Institute, University of Groningen（格罗宁根大学卡普坦天文研究所）；Escola de Enxeñaría de Telecomunicación, Universidade de Vigo（维戈大学电信工程学院）；Universidad de La Laguna（拉古纳大学）；Osservatorio Astronomico di Abruzzo, INAF（阿布鲁佐天文台，意大利国家天体物理研究所）；INFN - Sezione di Pisa, Universit（意大利国家核物理研究所比萨分部）
The assembly history of NGC 1365 through chemical archaeology
Institute for Theory & Computation, Center for Astrophysics — Harvard & Smithsonian（哈佛-史密森尼天体物理中心理论计算研究所）；Research School for Astronomy & Astrophysics, Australian National University（澳大利亚国立大学天文与天体物理研究学院）；ARC Centre of Excellence for All-Sky Astrophysics in 3 Dimensions (ASTRO 3D), Australian National University（澳大利亚国立大学三维全天空天体物理学卓越研究中心）；Department of Astronomy, University of Florida（佛罗里达大学天文学系）；Department of Astronomy, University of Virginia（弗吉尼亚大学天文学系）；Virginia Institute for Theoretical Astronomy, University of Virginia（弗吉尼亚大学理论天文学研究所）；The Observatories, Carnegie Institution for Science（卡内基科学机构天文台）；Department of Astrophysical Sciences, Princeton University（普林斯顿大学天体物理科学系）
通过分析 NGC 1365 的高分辨率氧丰度并结合 IllustrisTNG 模拟，揭示星系盘、棒和气体盘分别由不同时期合并事件组装的历史，证明化学考古学可追踪星系动力学演化。
Large gas inflow driven by a matured galactic bar in the early Universe
National Astronomical Observatory of Japan（日本国立天文台）；Nagoya University（名古屋大学）；The Graduate University for Advanced Studies (SOKENDAI)（日本高等研究院（SOKENDAI））；Institute for Advanced Research, Nagoya University（名古屋大学先进研究学院）；The University of Tokyo（东京大学）
Extragalactic Planetary Nebulae (xPNe). Chemical evolution and assembly histories of nearby galaxies using Oxygen and Argon abundances. From the local universe to cosmic dawn
