The Fossil Record of Galaxy Formation: Cosmology on Galaxy and Cluster Scales

星系形成的化石记录：星系和星团尺度的宇宙学

• 批准号: RGPIN-2017-04049
• 负责人: Cote, Patrick
• 金额: $ 2.62万
• 依托单位: University of Victoria
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=710794
• 关键词: Fossil; Record; Galaxy; Formation; Cosmology

The Lambda Cold Dark Matter (CDM) "standard" model is remarkably successful in matching cosmological observations on spatial scales larger than about 1 Mpc. But when astronomers look on smaller scales -- i.e., on the scales of galaxies and galaxy clusters -- a number of problems emerge. The predictions of the model disagree with the observed numbers of low-mass galaxies in the local universe, the measured central mass distributions in those galaxies, and the dynamical masses of the Milky Way's brightest companions. Understanding these discrepancies has become a top priority for the international astrophysics community, and the last 5-10 years has seen significant progress on both the observational and theoretical fronts. In terms of theory, a new generation of hydrodynamical simulations having high dynamic range and high mass resolution, and employing increasingly sophisticated treatments of the physical processes that are believed to be important for galaxy formation, are being brought to bear on the problem. Observationally, new instruments and telescopes are being used to study the faintest and lowest-mass stellar systems, as these objects provide especially stringent tests of the models. This scrutiny has already produced some surprises: e.g., the existence of some exceptionally diffuse galaxies in cluster environments; large numbers of dense nuclei (some of which contain super-massive black holes) at the centres of intermediate- and low-mass galaxies; thin stellar streams in the Galactic halo that trace the remains of disrupted galaxies; rich populations of star clusters found in a diversity of environments whose numbers appear to scale in proportion to dark matter mass; and an ever-increasing number of "ultra faint" dwarf galaxies in the Milky Way that appear to be the most dark matter dominated systems in the universe. Over the past decade, I have been a founder, or co-founder, of some of the largest observing programs ever to use the local universe as a testing ground for cosmological models of structure formation. State-of-the-art UV/optical/IR imaging -- mainly from the Canada-France-Hawaii Telescope and the Hubble Space Telescope -- are being used, along with spectroscopy from 4-10m-class telescopes, to explore the properties of the stellar systems in two complementary environments: the Virgo Cluster, the nearest rich cluster of galaxies, and the halo of the Milky Way. My graduate students, whose continued support would be made possible with this grant, are leading two key elements of this program: (1) characterizing the total masses (including black hole content), star formation histories and chemical enrichment histories of galactic nuclei and establishing their connection to other types of compact stellar systems; and (2) using white dwarfs, blue horizontal branch stars and metal-poor stars to explore the stellar populations, structure and evolution of the halo and disk.

Lambda冷暗物质（CDM）“标准”模型在大于1 Mpc的空间尺度上非常成功地匹配了宇宙学观测。但是，当天文学家在更小的尺度上观察时，即在星系和星系团的尺度上，出现了许多问题。该模型的预测与观测到的本地宇宙中低质量星系的数量、测量到的这些星系的中心质量分布以及银河系最亮的伴星的动态质量不一致。了解这些差异已经成为国际天体物理学界的首要任务，在过去的5-10年里，在观测和理论方面都取得了重大进展。