2008A&A...480..349P


Query : 2008A&A...480..349P

2008A&A...480..349P - Astronomy and Astrophysics, volume 480, 349-357 (2008/3-3)

The nitrogen and oxygen abundances in the neutral gas at high redshift.

PETITJEAN P., LEDOUX C. and SRIANAND R.

Abstract (from CDS):

We study the oxygen and nitrogen abundances in the interstellar medium of high-redshift galaxies. We use high resolution and high signal-to-noise ratio spectra of damped Lyman-α (DLA) systems detected along the line-of-sight to quasars to derive robust abundance measurements from unsaturated metal absorption lines. We present results for a sample of 16 high-redshift DLAs and strong sub-DLAs (logN(HI)>19.5, 2.4<zabs<3.6) including 13 new measurements. We find that the oxygen to iron abundance ratio is pretty much constant with [O/Fe]~+0.32±0.10 for -2.5<[O/H]←1.0 with a small scatter around this value. The oxygen abundance follows quite well the silicon abundance within ∼0.2dex, although the silicon abundance could be slightly smaller for [O/H]←2. The distribution of the [N/O] abundance ratio, measured from components that are detected in both species, is somehow double peaked: five systems have [N/O]>-1 and nine systems have [N/O]←1.15. In the diagram [N/O] versus [O/H], a loose plateau is possibly present at [N/O]~-0.9, which is below the so-called primary plateau as seen in local metal-poor dwarf galaxies ([N/O] in the range -0.57 to -0.74). No system is seen above this primary plateau whereas the majority of the systems lie well below with a large scatter. All this suggests a picture in which DLAs undergo successive star-bursts. During such an episode, the [N/O] ratio decreases sharply because of the rapid release of oxygen by massive stars, whereas inbetween two bursts, nitrogen is released by low and intermediate-mass stars with a delay and the [N/O] ratio increases.

Abstract Copyright:

Journal keyword(s): ISM: abundances - Galaxy: abundances - galaxies: quasars: absorption lines

Nomenclature: Table 1: [PLS2008] QSO JHHMM+DDMM abs N.NNNNN N=28. Table 2: [PLS2008] QSO JHHMM+DDMM abs N.NNN N=15.

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 - 2023
#notes
1 QSO J0003-2603 QSO 00 03 22.9531962024 -26 03 18.304471908   18 17.53     ~ 285 0
2 QSO J0105-1846 QSO 01 05 16.7912097864 -18 46 41.986634736     18.3     ~ 76 0
3 QSO B0112-30 QSO 01 15 04.8742901280 -30 25 14.952952308           ~ 47 1
4 QSO B0347-383 QSO 03 49 43.6603590912 -38 10 30.825444900     17.3     ~ 188 0
5 QSO B0841+129 BLL 08 44 24.2445546984 +12 45 46.526286780   18.28 18.5     ~ 116 0
6 QSO B0913+0715 QSO 09 16 13.9618240848 +07 02 24.497778588     17.1     ~ 102 0
7 QSO B1108-07 QSO 11 11 13.600 -08 04 02.00     18.10     ~ 70 0
8 QSO B1337+11 QSO 13 40 02.5419344664 +11 06 30.181521168     18.7     ~ 113 0
9 QSO J1342-1355 QSO 13 42 58.8724541136 -13 55 59.812504788   19.2 19.2     ~ 23 0
10 QSO B1409+0930 QSO 14 12 17.2929417480 +09 16 24.707943048     18.6     ~ 61 0
11 QSO B1946+770 QSO 19 44 54.8532392016 +77 05 52.673448048     15.8     ~ 151 0
12 QSO B2059-360 QSO 21 02 44.6068720464 -35 53 07.081042308   19.18 18.62     ~ 55 0
13 LBQS 2206-1958A QSO 22 08 52.0729138920 -19 43 59.866776948   17.49 17.33     ~ 213 0
14 QSO B2332-094 QSO 23 34 46.4045250120 -09 08 12.250650732   19.21 18.62 18.07   ~ 78 0

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2023.02.04-10:14:34

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