2001A&A...369...42K


C.D.S. - SIMBAD4 rel 1.7 - 2020.10.28CET21:44:46

2001A&A...369...42K - Astronomy and Astrophysics, volume 369, 42-48 (2001/4-1)

HI 21 cm absorption in low (z) damped Lyman-α systems.

KANEKAR N. and CHENGALUR J.N.

Abstract (from CDS):

We report Giant Metrewave Radio Telescope (GMRT) 21 cm observations of two confirmed and one candidate low redshift damped Lyman-α systems (DLAS). HI absorption was detected in the two confirmed systems, at z=0.2378 and z=0.5247, with spin temperatures of 2050±200K and 330±70K respectively. The non-detection of absorption in the third (candidate) system places an upper limit on its optical depth, which in turn implies a 3σ lower limit of 850 K on its spin temperature. Ground based K-band imaging observations (Turnshek et al. 2000, in press) have identified the low Ts absorber with a spiral galaxy while the high Ts system appears to be an LSB galaxy. This continues the trend noted earlier by Chengalur & Kanekar (2000MNRAS.318..303C) of low spin temperatures for DLAS associated with spiral galaxies and high spin temperatures for those with no such association. Combining these new results with 21 cm observations from the published literature, we find that (1) The 21 cm equivalent width (EW21) of DLAS increases with increasing NHI. Further, absorbers associated with spiral galaxies have systematically higher EW21 at the same NHI than DLAS with no such association, (2) DLAS at high redshift (z>2) have small velocity spreads ΔV, while, at low redshift (z≲2), both large and small ΔV are observed. These trends are in qualitative agreement with hierarchical models of galaxy formation.

Abstract Copyright:

Journal keyword(s): galaxies: evolution - galaxies: formation - galaxies: ISM - cosmology: observations - radio lines: galaxies

Nomenclature: Table 1: [KC2001] QSO J0120-2701 abs N.NNNN N=1.

CDS comments: Table 1: The 2 other DLAs re already known: [RT2000] QSO J0954+1743 abs 0.2377, [RT2000] QSO J0830+2411 abs 0.5247.

Simbad objects: 14

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Number of rows : 14

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 QSO B0118-272 BLL 01 20 31.6632705443 -27 01 24.643168036   15.89 15.56 15.49   ~ 241 1
2 3C 48 QSO 01 37 41.2995845985 +33 09 35.079126038   16.62 16.20     ~ 2526 2
3 QSO B0439-4319 QSO 04 41 17.3385473794 -43 13 45.487081188   16.64 16.36 16.54 16.26 ~ 96 1
4 ICRF J054236.1+495107 Sy1 05 42 36.13789843 +49 51 07.2337251   18.45 17.80 17.210   ~ 1280 1
5 ICRF J074110.7+311200 Sy1 07 41 10.7032630079 +31 12 00.232776104   17.02 16.89 16.322   ~ 414 1
6 3C 196 Sy1 08 13 36.056090 +48 13 02.63597   18.36 17.79     ~ 484 2
7 7C 082754.29+242103.00 QSO 08 30 52.08619070 +24 10 59.8204032   17.62 17.26 16.30   ~ 470 1
8 [RNT2003] B2 0827+243 G1 ALS 08 30 52.51 +24 11 01.9   22.76       ~ 16 0
9 QSO J0854+2006 BLL 08 54 48.8749311881 +20 06 30.642936668   15.91 15.43 15.56   ~ 2024 1
10 [RKV2003] QSO J0954+1743 abs 0.2377 DLA 09 54 56.8236 +17 43 31.222           ~ 14 0
11 QSO B0952+179 QSO 09 54 56.82361250 +17 43 31.2222114   17.31 17.23     ~ 197 1
12 QSO J1130-1449 QSO 11 30 07.05259287 -14 49 27.3881476   17.17 16.90 16 16.97 ~ 631 1
13 4C -02.55 QSO 12 32 00.0157879377 -02 24 04.790684994   17.41 17.06 16.4   ~ 385 1
14 3C 295 Sy2 14 11 20.467 +52 12 09.52   22.34 20.80 18.54   ~ 903 5

    Equat.    Gal    SGal    Ecl

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2020.10.28-21:44:46

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