Detecting cold gas at intermediate redshifts: GMRT survey using Mg II systems

Neeraj Gupta; R. Srianand; P. Petitjean; P. Khare; D. J. Saikia; D. G. York

doi:10.1086/511153

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arXiv · astro-ph/0611836

Detecting cold gas at intermediate redshifts: GMRT survey using Mg II systems

Neeraj Gupta·R. Srianand·P. Petitjean·P. Khare·D. J. Saikia·D. G. York

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Abstract

Intervening HI 21-cm absorption systems at z > 1.0 are very rare and only 4 confirmed detections have been reported in the literature. Despite their scarcity, they provide interesting and unique insights into the physical conditions in the interstellar medium of high-z galaxies. Moreover, they can provide independent constraints on the variation of fundamental constants. We report 3 new detections based on our ongoing Giant Metrewave Radio Telescope (GMRT) survey for 21-cm absorbers at 1.10< z_abs< 1.45 from candidate damped Lyman_alpha systems. The 21-cm lines are narrow for the z_abs = 1.3710 system towards SDSS J0108-0037 and z_abs = 1.1726 system toward SDSS J2358-1020. Based on line full-width at half maximum, the kinetic temperatures are <= 5200 K and <=800 K, respectively. The 21-cm absorption profile of the third system, z_abs =1.1908 system towards SDSS J0804+3012, is shallow, broad and complex, extending up to 100 km/s. The centroids of the 21-cm lines are found to be shifted with respect to the corresponding centroids of the metal lines derived from SDSS spectra. This may mean that the 21-cm absorption is not associated with the strongest metal line component.

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Neeraj Gupta, R. Srianand, P. Petitjean, P. Khare, D. J. Saikia, D. G. York. 2006-11-28. Detecting cold gas at intermediate redshifts: GMRT survey using Mg II systems. https://doi.org/10.1086/511153

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