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HI with the GMRT

Published online by Cambridge University Press:  26 May 2016

J. N. Chengalur
J. N. Chengalur*
Affiliation:
National Center for Radio Astrophysics, TIFR, Post Bag No 3, Pune 411007, India

Abstract

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The Giant Metrewave Radio Telescope (GMRT) has recently come into operation. This paper reports on observations of the HI line made using the GMRT during its commissioning phase. These include observations of the nearby Low Surface brightness galaxy Cepheus 1, as well as of a number of low and medium redshift damped Ly-α systems. The derived spin temperatures for these systems is typically higher than that characteristic of the gas in the disk of the Galaxy. Higher spin temperatures were known to be characteristic of high redshift damped Ly-α absorbers, and had been earlier attributed to evolutionary effects. Our observations suggest that high spin temperatures are not a consequence of evolutionary effects since the look back time to these low z absorbers is modest. We also report on the short time scale (days) variability of the absorption profile of the z = 0.3127 system in front of B1127-145. This is the second damped Ly-α system to show such variation (the other being the z = 0.524 absorber in front of AO 0235+164).

Type
Part 2: Extra Galactic Neutral Hydrogen and Cosmology
Information
Symposium - International Astronomical Union , Volume 199: The Universe at Low Radio Frequencies , 2002 , pp. 96 - 101
Copyright
Copyright © Astronomical Society of the Pacific 2002 

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