  Active galactic nuclei (AGNs) are key for understanding the coevolution of
galaxies and supermassive black holes (SMBHs). AGN activity is thought to
affect the properties of their host galaxies, via a process called "AGN
feedback", which drives the co-evolution. From a parent sample of 1151 z < 1
type-1 quasars from the Sloan Digital Sky Survey quasar catalog, we detected
host galaxies of 862 of them in the high-quality grizy images of the Subaru
Hyper Suprime-Cam (HSC) survey. The unprecedented combination of the survey
area and depth allows us to perform a statistical analysis of the quasar host
galaxies, with small sample variance. We fit the radial image profile of each
quasar as a linear combination of the point spread function and the Sersic
function, decomposing the images into the quasar nucleus and the host galaxy
components. We found that the host galaxies are massive, with stellar mass
Mstar > 10^(10) Msun, and are mainly located on the green valley. This trend is
consistent with a scenario in which star formation of the host galaxies is
suppressed by AGN feedback, that is, AGN activity may be responsible for the
transition of these galaxies from the blue cloud to the red sequence. We also
investigated the SMBH mass to stellar mass relation of the z < 1 quasars, and
found a consistent slope with the local relation, while the SMBHs may be
slightly undermassive. However, the above results are subject to our sample
selection, which biases against host galaxies with low masses and/or large
quasar-to-host flux ratios.
