Kanekar, N. ; Subrahmanyan, R. ; Ellison, S. L. ; Lane, W. M. ; Chengalur, J. N. (2006) H I 21 cm absorption at z~ 2.347 towards PKS B0438-436 Monthly Notices of the Royal Astronomical Society: Letters, 370 (1). L46-L50. ISSN 1745-3925
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Official URL: http://onlinelibrary.wiley.com/doi/10.1111/j.1745-...
Related URL: http://dx.doi.org/10.1111/j.1745-3933.2006.00186.x
Abstract
We report the detection of redshifted H i 21-cm absorption in the z~2.347 damped Lyman absorber (DLA) towards PKS B0438-436 with the Green Bank Telescope. This is the second-highest redshift at which 21-cm absorption has been detected in a DLA. The absorption extends over ˜60 km s−1 and has two distinct components, at z= 2.347 477(12) and z= 2.347 869(20). A similar velocity structure is seen in optical metal lines, although the peak absorption here is offset by ~11 km s−1 from the peak in the 21-cm line. We obtain a high spin temperature Ts~ (886 ±248) × (f/0.58) K, using a covering factor estimated from 2.3-GHz very long baseline interferometry data. However, the current data cannot rule out a low spin temperature. The non-detection of CO 3-2 absorption places the upper limit NCO < 3.8 × 1015 (Tx/10) cm−2 on the CO column density.
Item Type: | Article |
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Source: | Copyright of this article belongs to John Wiley and Sons. |
Keywords: | Galaxies: High-redshift; Galaxies: ISM; Radio Lines: Galaxies |
ID Code: | 63550 |
Deposited On: | 29 Sep 2011 04:07 |
Last Modified: | 29 Sep 2011 04:07 |
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