The Role of Star-Formation and AGN in Dust Obscured Galaxies
Roebuck, Eric.
2019
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A key question in extragalactic studies is the determination of the relative roles of stars and AGN in powering dusty galaxies at z~0.5-3, i.e. the epoch of Cosmic Noon, where the bulk of star-formation and AGN activity took place. In this thesis, I use a library of hydrodynamic simulations with dust radiative transfer of isolated and merging galaxies to investigate several inter-related questions ... read moreabout dusty galaxies at cosmic noon. In Paper I, I investigate how well the simulations reproduce empirical IR AGN fraction estimates for a large sample of observed dusty galaxies at z~0.5-3. I also determine how IR AGN fractions relate to the UV-mm AGN fractions as a function of level of dust obscuration. In Paper II, I investigate in what circumstances the IR luminosity that is not due to an AGN is or is not a good proxy for the star-formation rate. I test recently proposed methods for correcting the IR luminosity for the contribution of intermediate age stars. I also propose a new method to do so that works better in rapidly quenching post-starburst regimes. I also show that our simulations show variable dust attenuation curves, broadly consistent with recent observations, and discuss the implications of this for common methods of classifying the evolutionary stage of galaxies. In Paper III (in progress) I investigate the degree to which the best-fit SED is a good predictor of the merger stage of a galaxy or its gas fraction. In the appendix, I discuss some technical issues of fitting data to sparsely sampled simulations library. Finally, I present a summary of the key results in this thesis.
Thesis (Ph.D.)--Tufts University, 2019.
Submitted to the Dept. of Physics.
Advisor: Anna Sajina.
Committee: Danilo Marchesini, Cristian Staii, Mark Lacy, and Hugh Gallagher.
Keyword: Physics.read less - ID:
- k3569j14b
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