(Proposal ID) S10A-050

(PI) Tanaka, Masaomi

(Proposal Title)
Spectropolarimetry of Stripped-Envelope Supernovae and GRB-Supernovae

(Abstract)
We propose Target of Opportunity (ToO) spectropolarimetric observations of 
stripped-envelope core-collapse supernovae (SNe) and SNe associated with gamma-
ray bursts (GRB-SNe, a special class of stripped-envelope SNe) to study their 
explosion geometry. Probing asphericity of stripped-envelope SNe and GRB-SNe 
gives crucial constraints on the explosion mechanism of GRBs and SNe, which is 
one of the most important, unsolved questions in the modern astronomy. By 
obtaining high-quality spectropolarimetric data, we explore the three-
dimensional distribution of various elements in the SN ejecta. In addition, by 
following the time evolution, we correctly distinguish the intrinsic 
polarization from the interstellar polarization. The number of 
spectropolarimetric observations of stripped-envelope SNe so far is too small 
to understand common properties and diversity among stripped-envelope SNe and 
GRB-SNe. We aim to increase the number of multi-epoch spectropolarimetric 
samples of stripped-envelope SNe (only 5 examples so far). The number of 
stripped-envelope SNe discovered with magnitude sufficiently bright enough for 
spectropolarimetry is expected to be ~3 per half a year and they are bright 
enough only for about 20 days. Thus, we need ToO observation.