Ly α emission at z ∼ z em around the quasar J 2233 − 606 in the Hubble Deep Field South ?

The STIS Hubble Deep Field South around the quasar J2233−606 was observed in the course of the VLT-UT1 Science Verification programme with the Test Camera in two broad-band filters, B and R, and in a narrow-band filter roughly centered at the quasar emission redshift, zem = 2.238. The most striking result is the discovery of a giant Lyα nebulosity around this radio-weak quasar, with an overall extent of 9.2′′ × 12.1′′ or 121 × 159 h−2 50 kpc2 and a luminosity of 3.1 ×1044 h−2 50 erg s−1 (for q0 = 0), similar to those found around radio-loud quasars and radio galaxies. There are three additional emissionline candidates in a 1.11′ × 1.24′ field with an observed Lyα flux above our 3σ Lyα detection limit of 1.9 × 10−17 erg s−1 cm−2 for point sources. The resolved bright object located 4.9′′ north-east of the quasar, which has recently been identified as a galaxy at zg = 0.57, has an associated, weak Mg ii absorption in the quasar spectrum.