Dissertation Defense: Tonima Tasnim Ananna, Yale University, “ACCRETION HISTORY OF AGN: X-RAY POPULATION SYNTHESIS MODEL & MULTIWAVELENGTH PHOTOMETRIC REDSHIFTS”

This work presents a new model which describes the space densities of Active Galactic Nuclei (AGN) over cosmic time, at different levels of obscuration. We find that more than 50% of AGN in the local Universe are heavily obscured, which is much higher than previous estimates for such populations. Using this model, we also calculate a slightly higher average radiative efficiency of accreting black holes. As radiative efficiency is connected to spins of the central black holes, this result might indicate that more obscured objects have higher spins.
This work also reports photometric redshifts (distances) to ~6000 X-ray selected AGN in Stripe 82x field.

Thesis Advisor: Meg Urry (meg.urry@yale.edu)