Synchronized co-evolution of supermassive black holes and their host galaxies with HSC

We exploit the unique combination of wide-area coverage, deep depth, and superb spatial resolution of the optical imaging from the Hyper Suprime-Cam (HSC) Subaru Strategic Program to establish the relationship between quasars and their host galaxies beyond the local universe (Li et al. 2021a,b). Using ~5000 SDSS quasars at 0.2 < z < 1, we decompose their optical light into the unresolved quasar and extended galaxy contribution with careful consideration of the point-spread function. With five HSC bands (grizy) and SED-fitting, the stellar masses of their host galaxies (10 < log M_* < 11.5) are measured with a high level of reliability based on extensive simulations. As a critical component for this study, a forward-modeling of the sample with the observational selection applied is required to interpret the results. Using black hole masses available in the literature (7 < log M_BH < 9.5) , we are able to place constraints of the evolution of the ratio (M_BH/M_*) between supermassive black holes and their hosts. With little sign of intrinsic evolution, there is a degeneracy with the intrinsic scatter which appears to be consistent with the local dispersion and indicate the need for quasar feedback to maintain the constant mass ratio with cosmic time as supported by hydrodynamic simulations. We will further discuss the sizes of quasar hosts and their relation to the general galaxy population which has implications on the growth of their bulges. Our study highlights the science to come from larger imaging surveys with Rubin Observatory, Euclid and WFIRST.