Deciphering the cosmic star formation history and the Nature of Type Ia   Supernovae by Future Supernova Surveys
  We investigate the prospects of future supernova searches to get meaningful constraints about the cosmic star formation history (CSFH) and the delay time of type Ia supernovae from star formation (tau_{Ia}), based only on supernova data. Here we parameterize the CSFH by two parameters, alpha and beta that are the evolutionary indices (proportional to (1+z)^{alpha, beta}) at z <~ 1 and >~ 1, respectively, and quantitatively examined how well the three parameters (alpha, beta, and tau_{Ia}) can be constrained in ongoing and future supernova surveys. We found that the type classification of detected supernovae down to the magnitude of I_{AB} ~ 27 is essential, to get useful constraint on beta. The parameter tau_{Ia} can also be constrained within an accuracy of ~ 1--2 Gyr, without knowing alpha that is somewhat degenerate with tau_{Ia}. This might be potentially achieved by ground-based surveys but depending on the still highly uncertain type-classification by imaging data. More reliable classification will be achieved by the SNAP mission. The supernova counts at a magnitude level of I_{AB} or K_{AB} ~ 30 will allow us to break degeneracies between alpha and tau_{Ia} and independently constrain all the three parameters, even without knowing supernova types. This can be achieved by the SNAP and JWST missions, having different strength of larger statistics and reach to higher redshifts, respectively. The dependence of observable quantities on survey time intervals is also quantitatively calculated and discussed. 
Takeshi Oda and Tomonori Totani (Kyoto)