(Proposal ID) S15A-032

(PI) Totani, Tomonori

(Proposal Title)
 Follow-up of Fast Radio Bursts to Discover Other-Wavelength Counterparts

(Abstract)
Fast Radio Bursts (FRBs) are a mysterious transient phenomenon whose duration 
is only a few msec. No repeating events or counterparts in other wavelengths 
have been detected, but their dispersion measures imply that they are located 
at cosmological distances of z ~ 0.5--1. We propose HSC/Suprime-Cam follow up 
of FRBs to find the first ever counterpart at other wavelengths, by using the 
unique capability of Subaru to cover the entire FRB error regions (14 arcmin 
diameter FWHM) with 8m-class sensitivity. We have set up the collaboration 
with the FRB search team using the Parkes radio observatory, and expect more 
than one FRB events observable by Subaru in the S15A semester.  We choose 
1--10 days after a FRB alert as the follow-up time scale, which is optimized 
to verify the two proposed hypotheses for the FRB origin: mergers of double 
white dwarf or double neutron star binaries. These scenarios predict a 
detectable SN Ia or kilonova associated with a FRB.  It is also possible that 
an optical/NIR counterpart is reported by other observatories or found by our 
own imaging, and hence we also request to use optical/NIR spectroscopic 
instruments of Subaru (or Gemini) for the follow-up when the counterpart is 
bright enough for spectroscopy.