A Survey for Hα emitting galaxies AT z ≃ 2.2

Abstract

The deepest survey for Hα emitting galaxies at z ≃ 2.2has recently been made in narrow-band (≃ 1%) filters around2.1μm using SOFI at the ESO NTT telescope. An effective area of≃ 100 sq. arcmin and a comoving volume of 9000 Mpc³ (forH₀ = 50, q₀ = 0.5) has been covered to a volume weighted 3σ line flux limit of ≃ 5 × 10^-17 erg s^-1cm^-2. Our survey covered the WFPC2 and STIS fields in the HubbleDeep Field South and an anonymous field about 30 deg. away. Thefaintest limit reached was 3 × 10^-17 erg s^-1 cm^-2 onthe WFPC2 field. In total, 10 convincing candidates with deduced starformation rates in the range 9 - 50 M⊙/yr and an equal number ofmarginal ones have been identified for confirmation and follow-upspectroscopy with ISAAC at the VLT. Based on a very preliminaryanalysis we compare our results with those of earlier surveys andbriefly discuss some possible implications for the form of theevolution out to z ≃ 2 and the effects of clustering.