Death rate of massive stars at redshift ∼0.3

We report the first result of a supernova search program designed to measure the evolution of the supernova rate with redshift. To make the comparison with local rates more significant we copied, as much as possible, the same computation recipes as for the measurements of local rates. Moreover, we exploited the multicolor images and the photometric redshift technique to characterize the galaxy sample and accurately estimate the detection efficiency. Combining our data with the recently published measurements of the SN Ia rate at different redshifts, we derived the first, direct measurement of the core collapse supernova rate at z = 0.26 as r(cc) = 1.45(-0.45)(+0.55) h(2) SNu [h = H-0/75]. This is a factor of three (+/-50%) larger than the local estimate. The increase for a look back time of 2.8 Gyr is more rapid than predicted by most of the published models of SN rate evolution. Core-collapse SN rates measure the death rate of massive stars and, because of the short time scale of evolution, can be translated into a measurement of the ongoing SFR. Assuming a Salpeter IMF and the standard scenario for core-collapse progenitors we derived an estimate of the star formation rate at redshift 3.1(-1.0)(+1.1) x 10(-2) h(3) M. yr(-1) Mpc(-3) which compares very well with a recent estimate based on the measurement of the Halpha luminosity density at the same redshift.