Speaker
Description
Determining when and where supermassive black hole growth - seen as Active Galactic Nuclei (AGN) - occurs within the evolving galaxy population is vital to understand the physical mechanisms that drive the growth of black holes as well as what triggers periods of AGN activity, and the impact of AGN feedback on galaxy growth. However, linking galaxy and AGN properties is complicated by the variability of AGN activity on timescales that are short compared to galaxy-wide processes, blurring out any direct correlation and requiring careful and extensive statistical studies to reveal any underlying link. In this talk, I will review the progress over the last few years that has been achieved using large X-ray surveys (primarily from Chandra and XMM-Newton) to quantify the incidence of AGN activity across the evolving galaxy, including measurements of AGN fractions, the overall distributions of accretion rates, and averaged black hole accretion rates that are vital for quantifying black hole growth. I will present the emerging picture where the bulk of AGN activity is associated with star-forming galaxies, suggesting cold gas as a common origin for both star formation and the (stochastic) triggering of AGN. Nonetheless, enhancements in the AGN fraction are found in other galaxy populations, such as passively evolving quiescent galaxies, suggesting a broader range of triggering mechanisms. Finally, I will discuss remaining difficulties in accounting for the assembly of the most massive black holes and how the unprecedented surveys with eROSITA have the potential to address this issue.
