2002MNRAS.337..369T

We describe ISAAC/ESO-VLT observations of the Hαλ6563 Balmer line of 33 field galaxies from the Canada-France Redshift Survey (CFRS) with redshifts selected between 0.5 and 1.1. We detect Hα in emission in 30 galaxies and compare the properties of this sample with the low-redshift sample of CFRS galaxies at z ∼ 0.2. We find that the Hα luminosity, L (Hα), is tightly correlated to M ( B_AB) in the same way for both the low- and high-redshift samples. L (Hα) is also correlated to L ([Oii]λ3727), and again the relation appears to be similar at low and high redshifts. The ratio L (lsqb;Oii])/ L (Hα) decreases for brighter galaxies by as much as a factor of 2 on average. Derived from the Hα luminosity function, the comoving Hα luminosity density increases by a factor 12 from <z >= 0.2 to <z >= 1.3 . Our results confirm a strong rise of the star formation rate (SFR) at z < 1.3, proportional to (1 +z) ^4.1±0.3 (with H₀= 50 km.s^–1 Mpc ^–1, q₀= 0.5). We find an average SFR(2800 Å)/SFR (Hα) ratio of 3.2 using the Kennicutt SFR transformations. This corresponds to the dust correction that is required to make the near-ultraviolet data consistent with the reddening-corrected Hα data within the self-contained, I -selected CFRS sample.