S21B0027

As the booming development of wide-field survey facilities, breakthroughs in time-domain astronomy have been made in 2010s. The large aperture of the Subaru telescope and the wide field-of-view of the Hyper Suprime-Cam (HSC) make Subaru/HSC the most powerful survey facility of studying type Ia supernovae (SNe Ia) soon after their explosions. Here, we propose an HSC deep multiband survey which is optimized to catch the first light of SNe Ia at redshifts below 0.1. By balancing the observing depth, survey period, and total survey area of the Subaru/HSC observation, four ultra-early SNe Ia with brightness >∼ 500 times fainter than the peak can be discovered, and particularly, the deepest photometry of early-phase SNe Ia by far can be promisingly achieved. The deepest early-phase photometry and ultra-early spectroscopies with Subaru/HSC and synergistic Gemini/GMOS observations not only can tightly constrain or directly identify/rule out specific kinds of single-degenerate progenitor systems but also can test the double white-dwarf merger scenario by constraining the nearby CSM distribution for the first time. Furthermore, our survey data will bring a great legacy value to the Japanese astronomical community in the era of space survey missions.

This document was translated from L^AT_EX by H^EV^EA.