Joint Astrophysical Colloquium
A Subaru wide-field survey for faint and obscured quasars at high redshift
Yoshiki Matsuoka (Ehime University)
Thursday 18/09/2025 @ 11:30, Sala Antonio Sollima (IV piano Battiferro)
Quasars at high redshift (z > 6) are an important and unique probe of the distant Universe, for understanding the origin and progress of cosmic reionization, the early growth of supermassive black holes, and the evolution of the host galaxies and dark matter halos. The past few decades have seen extensive efforts to discover high-z quasars from wide-field (>100-deg2 class) surveys, including SDSS, CFHTLS, Pan-STARRS1, DES, UKIDSS, and VISTA surveys. When we started our project with Subaru Hyper Suprime-Cam (HSC), roughly 100 high-z quasars were known, but they were mostly limited to very luminous quasars due to the survey sensitivities. This talk will begin with a brief review of the motivations and history of those surveys, with a brief mention to the recent discoveries by JWST. Then I will introduce our “Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs)” project, which has discovered ~200 low-luminosity quasars at 5.6 < z < 7.1 over the past 10 years. The direct outcome and latest results from the follow-up observations will be presented. Finally, I will touch on some future prospects, including a massive spectroscopic survey with Subaru Prime Focus Spectrograph (PFS) which has just started.