ATCA search for 21 cm emission from a candidate damped Ly-alpha absorber at z = 0.101

Abstract

We report a deep search for 21 cm emission/absorption from the z ~ 0.101 candidate damped Lyman-alpha system towards PKS 0439-433, using the Australia Telescope Compact Array (ATCA). The spectrum shows a weak absorption feature - at the 3.3 sigma level - which yields a lower limit of 730 K on the spin temperature of the system. No H i emission was detected: the 3sigma upper limit on the H i mass of the absorber is 2.25 109 Msun, for a velocity spread of ~ 70 km s-1. The low H i mass and the high spin temperature seem to rule out the possibility that the absorber is a large gas-rich spiral galaxy.