A statistical investigation into the relationship between supermassive black hole growth and star formation

In an attempt to reveal whether any coevolution between a central SMBH and its host galaxy exists, the literature has sought to identify whether the growth rates of the two are connected (witnessed as Active Galactic Nuclei, AGN, and star-formation respectively). However, depending on the sample selection method, there appears to be a contradiction in the results, with those studies selecting a galaxy sample reporting a positive correlation and those studies selecting an AGN sample reporting a at relationship. In order to include non-detections in the analysis, the majority of these studies resort to a binning-and-averaging approach and thus investigate how the average star-formation changes across AGN power bins, or vica versa. However, binning and averaging both have limitations.

In this thesis, we conduct a detailed statistical analysis of the relationship between the SMBH accretion rate and the star formation rate (SFR) of the host galaxy. We firstly investigate how the full distribution of SMBH accretion rates changes between galaxies with excess star formation (i.e., starburst galaxies) and those with lower levels of star formation. Secondly, we investigate how the full distribution of star-forming properties changes between high and low power AGNs, before moving on to present a binning-free methodology to investigate how the same distribution changes continuously with AGN power. Therefore, conducting analyses that moves beyond the binning-and-averaging approach. In general, we �nd a statistical connection between SMBH accretion rate and SFR likely exists such that more rapidly accreting SMBHs tend to reside in galaxies with higher levels of star formation. We propose that this scenario is consistent with a proposed coevolution of SMBH and galaxy growth in that they are both cogoverned by cold molecular gas availability in the host galaxy.