MAPPING THE LINKS BETWEEN STARS, GAS, AND DARK MATTER WITH LARGE SURVEYS

Galaxy formation;Large surveys;Physics

Lan, Ting-wenMénard, Brice ;

Johns Hopkins University

关键词: Galaxy formation;    Large surveys;    Physics;   

Others  :  https://jscholarship.library.jhu.edu/bitstream/handle/1774.2/39704/LAN-DISSERTATION-2016.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: JOHNS HOPKINS DSpace Repository

【 摘 要 】

The evolution of galaxies is driven by complex interplay between multiple components of the Universe, including stars, gas, and dark matter. To advance our understanding of galaxy evolution, it is essential to characterize the interactions between these components. This dissertation explicates the applications of statistical techniques for extracting new information from large survey data in order to investigate the relationships between stars, gas and dark matter.By employing the cross-correlation technique which is developed to extract relevant signals in spectroscopic and photometric datasets, I study the connections between galaxies and dark matter halos. I characterize the galaxy luminosity functions in halos with different masses. This new observation uncovers an ubiquitous upturn at the faint-end of the luminosity functions, suggesting that it is formation that regulate the stellar mass of satellite galaxies. With a simple model, I show that the shape of the luminosity functions can be used to infer the formation history of galaxies.Applying the same technique, I study the relationships between galaxies and gas around them, the circumgalactic medium.I robustly characterize the spatial distribution of gas and reveal that the cool gas around star-forming galaxies and those around passive galaxies exhibit different behaviors. This result demonstrates that the dichotomy of galaxy types is reflected in the circumgalactic medium.Finally, I explore the diffuse interstellar bands, a set of mysterious absorption lines ubiquitously seen in the interstellar medium of our Milky Way. I map the distribution of 20 different DIBs across the sky by using about half a million of SDSS spectra of quasars, galaxies, and stars. Using the map, I show that the DIB carriers have different sensitivity to the physical conditions in the ISM.The results of the dissertation demonstrate that combining large survey data and statistical techniques is a powerful and promising approach to study galaxy formation and evolution. Pursuing this direction, one can uncover new astronomical phenomena and make great progress in our understanding of galaxy formation and evolution.