Understanding the Early Stage of Cluster Formation
Abstract
Understanding the formation and evolution of galaxies is a crucially important task in modern astronomy. It is well known that galaxy formation is strongly affected by the environments they reside in. Galaxy clusters, as the densest large-scale structures in the Universe, thus serve as ideal laboratories to study how galaxy formation proceeds in dense environments. Clusters already began to form at z > 2, therefore to directly witness the early stage of galaxy formation in dense environments, it is necessary to identify progenitors of clusters (‘protoclusters’) and study their galaxy constituents within. In this thesis, I present two observational studies on high-redshift protoclusters at z > 3. Utilizing multiwavelength data and different galaxy selection techniques, significant galaxy overdensities are found in the two protoclusters, which are predicted to evolve into Coma-like clusters by present day. Various types of galaxies are identified in the protocluster, such as normal star-forming galaxies, massive quiescent galaxies and post-starburst galaxies. Together with extreme and rare sources such as giant Lyman-alpha nebulae and brighest cluster galaxy, they paint a picture of how different galaxy populations trace the underlying dark matter halos. Finally, the environmental impact on galaxy properties appears to be a subtle one for these protoclusters, which might depend on the galaxy population one chooses to study.
Degree
Ph.D.
Advisors
Lee, Purdue University.
Subject Area
Analytical chemistry|Astronomy|Astrophysics|Atomic physics|Chemistry|Energy|Optics|Physics|Theoretical physics
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