Poster Presentation

Stacking analysis of quasar host galaxies at z > 1 with the Subaru Hyper Suprime-Cam data

Author(s): Yuya Saeda, Toru Ishino, and Yoshiki Matsuoka (Ehime University)

Presenter: Yuya Saeda (Ehime University)

It is still unclear when and how supermassive black holes are activated as
AGNs. In this respect, it is crucial to reveal which type(s) of galaxies
host AGNs, by investigating colors and morphology of quasar host galaxies.
In particular, in order to understand relation between AGN activity and the
host galaxies in the early phase of the cosmic history, measurements of
quasar host galaxies located at z > 1 are necessary. However, it is
difficult to individually detect quasar host galaxies at z > 1 because of
high brightness of quasar nuclei. One way to overcome this issue is a
stacking analysis technique, which we exploit in our study.
In this study, by analyzing Hyper Suprime-Cam (HSC) Subaru Strategic
Program imaging data, we investigated the property of 3,527 quasar host
galaxies at z > 1 selected from the SDSS quasar catalog. We subtracted AGN
component with PSF models from the HSC images, and then stacked the
residual host galaxy components in a few redshift bins. We performed
aperture photometry on the stacked images in the HSC g, r, i, z, y bands,
and measured luminosity and colors of the host galaxies with SED fitting.
Our preliminary results indicate that quasar host galaxies at z > 1 are
located from the blue cloud to the green valley of the galaxy distribution,
which may point to a significant role that AGNs have played to regulate
star formation in the host galaxies.