The H α luminosity function and star formation rate up to z ∼ 1 ⋆ L . Tresse , 1 †

ABSTRACT We describe ISAAC/ESO-VLT observations of the Hα λ6563 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 (Tresse & Maddox 1998). We find that the Hα luminosity, L(Hα), is tightly correlated to M(BAB) in the same way for both the lowand high-redshift samples. L(Hα) is also correlated to L([O II]λ3727), and again the relation appears to be similar at low and high redshifts. The ratio L([O II])/L(Hα) decreases for brighter galaxies by as much as a factor 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) (with H0 = 50 km s −1 Mpc, q0 = 0.5). We find an average SFR(2800Å)/SFR(Hα) ratio of 3.2 using the Kennicutt (1998) SFR transformations. This corresponds to the dust correction that is required to make the near UV data consistent with the reddening-corrected Hα data within the self-contained, I-selected CFRS sample.