SIMBAD references

We present a measurement of the distant Type Ia supernova (SN Ia) rate derived from the first 2 yr of the Canada-France-Hawaii Telescope Supernova Legacy Survey. We observed four 1°x1° fields with a typical temporal frequency of <Δt≳4 observer-frame days over time spans of 158-211 days per season for each field, with breaks during the full Moon. We used 8-10 m class telescopes for spectroscopic follow-up to confirm our candidates and determine their redshifts. Our starting sample consists of 73 spectroscopically verified SNe Ia in the redshift range 0.2<z<0.6. We derive a volumetric SN Ia rate of r_V(<z≥0.47)=0.42^+0.13_–0.09(syst.)±0.06(stat.)x10^–4/yr Mpc³, assuming h=0.7, Ω_m=0.3, and a flat cosmology. Using recently published galaxy luminosity functions derived in our redshift range, we derive a SN Ia rate per unit luminosity of r_L(<z≥0.47)=0.154^+0.048_–0.033(syst.)^+0.039_–0.031(stat.) SN units. Using our rate alone, we place an upper limit on the component of SN Ia production that tracks the cosmic star formation history of 1 SN Ia per 10³ M_☉of stars formed. Our rate and other rates from surveys using spectroscopic sample confirmation display only a modest evolution out to z=0.55.