Formation of the first galaxies under stellar feedback




Jeon, Myoungwon

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The stellar feedback is a crucial ingredient for modeling galaxy formation, especially for the first galaxies, which are susceptible to stellar feedback due to their shallow potential wells. In this thesis I have investigated the impact of stellar feedback from the first generation of metal-free massive stars on the process of the first galaxy formation. I present the results of self-consistent, cosmological radiation hydrodynamics zoomed-in simulations of the formation and the evolution of the first galaxies. In particular, we focus on the role of different stellar feedback from first stars, such as photoionization heating from individual stars, X-ray feed- back from a singly accreting black hole and from a high-mass X-ray black hole, and mechanical and chemical feedback from a core-collapse or pair-instability supernova explosion, in shaping the gas in the interstellar medium out of which first galaxies were assembled. We find that the severity of the stellar feedback from the first generation of stars formed during the first galaxy assembly strongly determines the properties of the first galaxies. More massive first stars are likely to alter their host system in which they reside and likely to suppress further star formation, thus resulting in a simpler star formation history during the assembly of the first galaxies. We show that the first galaxies at redshifts z ≈ 10 are already complex metal-enriched systems, capable of forming, long-lived, normal stars. Finally, we also predict the observability of such system with the upcoming James Webb Space Telescope (JWST).



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