(Proposal ID) S17B-055I

(PI) Suzuki, Nao

(Proposal Title)
HSC Supernova Cosmology Legacy Survey with Hubble Space Telescope

(Abstract)
We propose to conduct a deep transient imaging survey with Hyper Suprime-Cam 
(HSC). Our originally scheduled SSP transient survey on SXDS was canceled due 
to the conflict with the mirror alminization schedule. To make the best use of 
awarded Hubble Space Telescope time (96 orbits), we redesigned the survey, 
aiming to go deeper than SSP in i and z. We have five science goals to probe 
the deep space in this program: 1) SNIa cosmology, 2) Type IIp SN cosmology, 
3) superluminous supernova cosmology, 4)Tidal disruption event and 5)Discovery 
of unknown type of transient. For SNIa cosmology, we expect to have 60 SNIa 
(z>1) with complete light curves, and we would like to have Gemini/GMOS 
spectroscopic follow-up time for the precise measurement of redshift. It would 
be ideal if we can send a sToO queue to Gemini/GMOS right after SNIa discovery 
by HSC. Combined with SSP transient program, we project to have 120 SNIa and 
its subset of 46 SNIa will have IR data point from HST which enables us to 
perform the most precise measurement of distances and dark energy. The 
expected Figure of Merit of 39 would be the highest among competing surveys. 
With HST, this program leaves a legacy of HSC with a footprint on the unknown 
world we are yet to discover.