We present measurements of the rates of high-redshift Type Ia supernovae derived from the Subaru/XMM-Newton Deep Survey ( SXDS ) .
We carried out repeat deep imaging observations with Suprime-Cam on the Subaru Telescope , and detected 1040 variable objects over 0.918 deg ^ { 2 } in the Subaru/XMM-Newton Deep Field .
From the imaging observations , light curves in the observed i ^ { \prime } -band are constructed for all objects , and we fit the observed light curves with template light curves .
Out of the 1040 variable objects detected by the SXDS , 39 objects over the redshift range 0.2 < z < 1.4 are classified as Type Ia supernovae using the light curves .
These are among the most distant SN Ia rate measurements to date .
We find that the Type Ia supernova rate increase up to z \sim 0.8 and may then flatten at higher redshift .
The rates can be fitted by a simple power law , r _ { V } ( z ) = r _ { 0 } ( 1 + z ) ^ { \alpha } with r _ { 0 } = 0.20 ^ { +0.52 } _ { -0.16 } ( stat . ) ^ { +0.26 } _ { -0.07 } ( syst . ) \times 10 ^ { -4 } { yr } ^ { -1 } { Mpc } ^ { -3 } , and \alpha = 2.04 ^ { +1.84 } _ { -1.96 } ( stat . ) ^ { +2.11 } _ { -0.86 } ( syst .
) .