Revealing the differences in the SMBH accretion rate distributions of starburst and non-starburst galaxies

We infer and compare the specific X-ray luminosity distributions for a sample of massive (i.e. log10(M*/M⊙) > 10.5) galaxies split according to their far-infrared-derived star-forming properties (i.e. starburst and non-starburst) and redshift. We model each distribution as a power law with an upper and lower turnover, and adopt a maximum likelihood method to include information from non-detections in the form of upper limits. When we use our inferred distributions to calculate the ratios of high to low sLX active galactic nuclei (AGNs; corresponding to above and below 0.1λEdd, respectively), we find that starbursts have significantly higher proportions of high sLX AGNs compared to their non-starburst counterparts. These findings help explain the increase in average X-ray luminosity in bins of increasing star formation rates reported by previous studies.