The Hα luminosity function and star formation rate up to z ∼ 1

We describe ISAAC/ESO-VLT observations of the Halpha lambda6563 Balmer line of 33 field galaxies from the Canada-France Redshift Survey (CFRS) with redshifts selected between 0.5 and 1.1. We detect Ha in emission in 30 galaxies and compare the properties of this sample with the low-redshift sample of CFRS galaxies at z similar to 0.2. We find that the Halpha luminosity, L(Halpha), is tightly correlated to M(B-AB) in the same way for both the low- and high-redshift samples. L(Halpha) is also correlated to L([O II]lambda3727), and again the relation appears to be similar at low and high redshifts. The ratio L([O II])/L(Halpha) decreases for brighter galaxies by as much as a factor of 2 on average. Derived from the Halpha luminosity function, the comoving Halpha 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 H-o = 50 km s(-1) Mpc(-1), q(0) = 0.5). We find an average SFR(2800 angstrom)/SFR(H alpha) 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 H alpha data within the self-contained, I-selected CFRS sample.