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2002MNRAS.332..383P - Mon. Not. R. Astron. Soc., 332, 383-391 (2002/May-2)
Molecular hydrogen at zabs=1.973 toward Q0013-004: dust depletion pattern in damped Lyman α systems.
PETITJEAN P., SRIANAND R. and LEDOUX C.
Abstract (from CDS):
The overall metallicities of this peculiar DLA system in which Oi and Cii are spread over ∼1050km.s–1 are [P/H]=-0.64, [Zn/H]=-0.74 and [S/H]=-0.82 relative to solar. The sub-DLA system at zabs=1.96753 has [P/H]>0.06, [Zn/H]>-0.02 and [S/H]>-0.18. The overall molecular fraction is in the range -2.7<logf ←0.6, which is the highest value found for DLA systems. H2 is detected in four components at -615, -480, 0 and 85km.s–1 relative to the strongest component at zabs=1.97296. CO is not detected [logN (CO)/N (Hi)←8] and HD could be present at zabs=1.97380.
We show that the presence of H2 is closely related to the physical conditions of the gas: high particle density together with low temperature. The observed excitation of high J H2 levels and the molecular fraction show large variations from one component to the other suggesting that the UV radiation field is highly inhomogeneous throughout the system. Gas pressure, estimated from Ci absorptions, is larger than what is observed in the ISM of our Galaxy. This, together with the complex kinematics, suggests that part of the gas is subject to high compression owing to either collapse, merging and/or supernovae explosions. This is probably a consequence of intense star formation activity in the vicinity of the absorbing gas.
Abstract Copyright: 2002 Blackwell Science Ltd
Journal keyword(s): galaxies: haloes - galaxies: ISM - quasars: absorption lines - quasars: individual: Q0013-004 - cosmology: observations
Nomenclature: [PSL2002] QSO J0016-0012 abs N.NNN N=1. Tables 1, 2: [PSL2002] QSO J0016-0012 abs N.NNNN, [PSL2002] QSO J0016-0012 abs N.NNNNN N=4+2.
Simbad objects: 2
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