ATCA search for 21 cm emission from a candidate damped Ly-α absorber at

¹ National Centre for Radio Astrophysics, Post Bag 3, Ganeshkhind, Pune 411 007, India
² Visiting Scientist, NFRA, PO Bus 2, 7990 AA Dwingeloo, The Netherlands e-mail: chengalu@ncra.tifr.res.in
³ Australia Telescope National Facility, CSIRO, Locked bag 194, Narrabri, NSW 2390, Australia e-mail: rsubrahm@atnf.csiro.au
⁴ Institut d'Astrophysique de Paris - CNRS, 98bis Boulevard Arago, 75014 Paris, France e-mail: ppetitje@iap.fr

Corresponding author: N. Kanekar, nissim@ncra.tifr.res.in

Received: 19 October 2000
Accepted: 1 December 2000

Abstract

We report a deep search for 21 cm emission/absorption from the candidate damped Lyman-α system towards PKS 0439-433, using the Australia Telescope Compact Array (ATCA). The spectrum shows a weak absorption feature -at the level -which yields a lower limit of 730 K on the spin temperature of the system. No H i emission was detected: the upper limit on the H i mass of the absorber is 2.25 10, 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.