(Proposal ID) S16A-106

(PI) Jiang, Jian

(Proposal Title)
Deep Multi-band Imaging Survey for Very Early Phase Type Ia Supernovae

(Abstract)
Despite their importance as powerful cosmological distance indicators, the 
origin of Type Ia supernovae (SNe Ia) is still obscured. Very early phase SN 
Ia (VESN Ia) observed within a few days after the explosion should play an 
irreplaceable role, and statistical study of VESNe Ia will become practically 
possible for the first time using Subaru/HSC as proposed here. Recently, a 
possible diversity in VESN Ia light curves (LCs) were found, and it could be 
interpreted by the companion-induced shock emission (CSE) and/or the off-center
 explosion scenario according to our further analysis. Soon after the work, 
the first two "abnormal" CSE-induced SNe Ia have been reported providing 
robust evidences for the single degenerate model and to some extent in favor 
of our speculation. In view of the great importance of SN Ia early color 
behavior in testifying the origin of the diversity between early phase LCs and 
tackling the long-standing issues of SN Ia progenitor and explosion we propose 
a 3-night Subaru/HSC observation for the first time to comprehensively 
investigate the multi-band photometric behavior of ~11 high-quality VESNe Ia. 
By combining early color information with LC behavior of such a large amount 
of VESN Ia samples groundbreaking studies on SN Ia can be well expected.