1205.4029 (N. Gupta et al.)

Search for cold gas in strong MgII absorbers at 0.5    [PDF]

N. Gupta, R. Srianand, P. Petitjean, J. Bergeron, P. Noterdaeme, S. Muzahid

We report 4 new detections of 21-cm absorption from a systematic search of 21-cm absorption in a sample of 17 strong (Wr(MgII 2796)>1A) intervening MgII absorbers at 0.5100 km/s are mainly seen towards the quasars with extended radio morphology at arcsecond scales. However, we do not find any correlation between the integrated 21-cm optical depth or DeltaV with the LS measured from the milliarcsecond scale images. All this can be understood if the absorbing gas is patchy with a typical correlation length of ~30-100 pc. We show that within the measurement uncertainty, the 21-cm detection rate in strong MgII systems is constant over 0.5View original: http://arxiv.org/abs/1205.4029