2006 (IPP)

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Author: search.filters.author.Gupta, NeerajSubject: search.filters.subject.Quasars

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    Multiwavelength investigation of a near-solar metallicity sub-DLA at Zabs=1.3647 towards PKS 0237-233
    (2006-11-10) Srianand, R.; Gupta, Neeraj; Petitjean, Patrick
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    Detecting cold gas at intermediate redshifts: GMRT survey using MgII systems
    (2006-11-28) Gupta, Neeraj; Srianand, R.; Petitjean, Patrick; et al.
    Intervening H i 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 ≤ zabs ≤ 1.45 from candidate damped Lyman-α systems. The 21-cm lines are narrow for the zabs= 1.3710 system towards SDSS J0108−0037 and zabs= 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, zabs=1.1908 system towards SDSS J0804+3012, is shallow, broad and complex, extending up to 100 km s−ᶥ . 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.