Simulating the galaxy population in the context of ΛCDM cosmology
Speaker: Qi Guo (NAOC)
Abstract: The CDM model has been successful in interpreting a wide variety of observations, including the cosmic microwave background fluctuations (CMB), the large-scale clustering of galaxies in the local universe, the high-redshift power spectrum probed by the Lyman α forest, the baryon fractions of galaxy clusters, and etc. Thanks to the development of powerful parallel supercomputers, current N-body simulations can follow the growth of representative samples of dark matter halos at high resolution and in their full cosmological context on scales ranging from those of rich clusters to those of dwarf galaxies. The dark matter is, however, invisible and verifiable descriptions of the nature and origin of the Universe have to rely on analysis of observables. Galaxy is one of the basic populations of light emitters. They form through the condensation of gas at the centers of a hierarchically aggregating population of dark matter haloes, and are thus excellent tracers of the cosmological structures. Their formation does not, however, trace that of their dark matter halos in a simple manner, and the exponentially growing body of high-qualitygalaxy data coming from large surveys cannot be properly compared to the CDM model without a careful treatment of baryonic processes. Such detailed comparison is the most promising route to clarifying the complex astrophysics underlying galaxy formation, and it may also uncover problems with the CDM model which are not evident on larger scales. Here I present the most up-to-date galaxy formation models in the context of CDM cosmology and discuss whether it is possible to distinguish different cosmologies with current galaxy surveys.
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