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arXiv · 1308.4410

Stringent constraints on the H I spin temperature in two z > 3 Damped Lyman-alpha systems from redshifted 21 cm absorption studies

Nirupam Roy·Smita Mathur·Vishal Gajjar·Narendra Nath Patra
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Abstract

Physical properties of Damped Lyman-alpha absorbers and their evolution are closely related to galaxy formation and evolution theories, and have important cosmological implications. H I 21 cm absorption study is one useful way of measuring the temperature of these systems. In this work, very strong constraints on the temperature of two Damped Lyman-alpha absorbers at z > 3 are derived from low radio frequency observations. The H I spin temperature is found to be greater than 2000 K for both the absorbers. The high spin temperature of these high-redshift systems is in agreement with the trend found in a compilation of temperatures for other Damped Lyman-alpha absorbers. We also argue that the temperature - metallicity relation, reported earlier in the literature, is unlikely to be a spurious line of sight effect, and that the redshift evolution of the spin temperature does not arises due to a selection effect. All of these are consistent with a redshift evolution of the warm gas fraction in Damped Lyman-alpha systems.

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Nirupam Roy, Smita Mathur, Vishal Gajjar, Narendra Nath Patra. 2013-08-20. Stringent constraints on the H I spin temperature in two z > 3 Damped Lyman-alpha systems from redshifted 21 cm absorption studies. https://doi.org/10.1093/mnrasl%2Fslt120

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