Observations of the high-redshift galaxy B2 0902+343 at 92 cm

Abstract

We present 92 cm observations of the high-redshift galaxy B2 0902+343 (z = 3.40) with the Westerbork Synthesis Radio Telescope (WSRT). Twenty-one cm H 1 is detected in absorption, at a depth of 15.9 mJy (=6σ) and rest frame velocity width 120 km s - 1 . We also report a null detection of OH emission or absorption at the 1665/1667 MHz rest-frame transitions. Based on our spectral sensitivity, we derive an upper limit on OH maser luminosity of log(L/L O .) < 5.2. In addition, we consider the possibility of absorption, and estimate a maximum column depth N(OH) of 1 x 10 1 5 cm - 2 , corresponding to at most 2 × 10 5 - 9 × 10 6 M O . of OH in the galaxy. The implications of these results are discussed in the context of current efforts to extend the OH megamaser luminosity function and galactic merger rate to high redshift.