2003A&A...403...55C


Query : 2003A&A...403...55C

2003A&A...403...55C - Astronomy and Astrophysics, volume 403, 55-72 (2003/5-3)

Early stages of nitrogen enrichment in galaxies: Clues from measurements in damped Lyman α systems.

CENTURION M., MOLARO P., VLADILO G., PEROUX C., LEVSHAKOV S.A. and D'ODORICO V.

Abstract (from CDS):

We present 4 new measurements of nitrogen abundances and one upper limit in damped Lyα absorbers (DLAs) obtained by means of high resolution (FWHM≃7km/s) UVES/VLT spectra. In addition to these measurements we have compiled data from all DLAs with measurements of nitrogen and α-capture elements (O, S or Si) available in the literature, including all HIRES/Keck and UVES/VLT data for a total of 32 systems, i.e. the largest sample investigated so far. We find that [N/α] ratios are distributed in two groups: 75% of the DLAs show a mean value of [N/α]=-0.87 with a scatter of 0.17dex, while the remaining 25% shows ratios clustered at [N/α]=-1.45 with an even lower dispersion of 0.05dex. The high [N/α]≃-0.9 plateau is consistent with the one observed in metal-poor HII regions of blue compact dwarf (BCD) galaxies ([N/α]=-0.73±0.13), while the [N/α]≃-1.5 values are the lowest ever observed in any astrophysical site. These low [N/α] ratios are real and are not due to ionization effects. They provide crucial evidence against the primary production of N by massive stars as being responsible for the plateau at -0.9/-0.7dex observed in DLAs and BCD galaxies. The transition between the low-N ([N/α]≃-1.5) and high-N ([N/α]≃-0.9) DLAs occurs at a nitrogen abundance of [N/H]≃-2.8, suggesting that the separation may result from some peculiarity of the nitrogen enrichment history. The [N/α]≃-1.5 values and their low dispersion are consistent with a modest production of primary N in massive stars; however, due to the limited sample, specially for the low-N DLAs, we cannot exclude a primary origin in intermediate mass stars as responsible for the low N abundances observed.

Abstract Copyright:

Journal keyword(s): cosmology: observations - galaxies: abundances - galaxies: evolution - quasars: absorption lines

Nomenclature: Tables 1, 9: [CMV2003] QSO JHHMM+DDMM abs N.NNN N=1+2.

CDS comments: Table 9: QXO 0001 not identified.

Simbad objects: 31

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Number of rows : 31
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 PHL 957 QSO 01 03 11.2741573824 +13 16 17.809871484   16.97 16.57     ~ 340 0
3 QSO B0201+113 QSO 02 03 46.65705710 +11 34 45.4094619   19.5 19.5 19.41   ~ 195 1
4 7C 020156.39+363507.00 QSO 02 04 55.5959081688 +36 49 17.992097868     18.1     ~ 119 1
5 QSO J0307-4945 QSO 03 07 22.8949808808 -49 45 48.274545240     18.76     ~ 59 0
6 QSO B0336-017 QSO 03 39 00.98616588 -01 33 17.6076051   20.1 19.1 18.8   ~ 107 2
7 QSO B0347-383 QSO 03 49 43.6603590912 -38 10 30.825444900     17.3     ~ 188 0
8 QSO B0528-2505 QSO 05 30 07.9627395840 -25 03 29.900044512   18.17 17.34 17.7   ~ 412 0
9 QSO J0745+4734 QSO 07 45 21.7878198936 +47 34 36.191801820   16.76 16.44     ~ 99 0
10 QSO B0841+129 BLL 08 44 24.2445546984 +12 45 46.526286780   18.28 18.5     ~ 116 0
11 9C J0933+2845 QSO 09 33 37.2819249600 +28 45 32.315668668   19.63 17.94 17.50   ~ 71 0
12 QSO B0940-1050 QSO 09 42 53.5078384704 -11 04 25.931336376   16.96 16.6 16.6   ~ 93 0
13 QSO J1057+4555 QSO 10 57 56.2610108784 +45 55 53.070401748   20.19 18.80 17.2 16.8 ~ 113 0
14 QSO B1117-1329 QSO 11 20 10.3163354592 -13 46 25.946998500     18.00     ~ 53 0
15 QSO B1122-168 QSO 11 24 42.8658917592 -17 05 17.389038732   16.5 16.5 16.1   ~ 126 1
16 QSO B1202-074 QSO 12 05 23.1360370080 -07 42 32.759842896     17.5     ~ 367 5
17 LBQS 1223+1753 QSO 12 26 07.1946195816 +17 36 49.921603812   18.93 18.59     ~ 109 0
18 LBQS 1232+0815 QSO 12 34 37.5514444464 +07 58 43.367750796     18.4     ~ 121 0
19 QSO B1409+0930 QSO 14 12 17.2929417480 +09 16 24.707943048     18.6     ~ 61 0
20 QSO B1425+606 QSO 14 26 56.1849081360 +60 25 50.813373324   16.82 16.54     ~ 137 0
21 QSO B1759+7539 BLL 17 57 46.3590423768 +75 39 16.181909928     16.50     ~ 85 0
22 QSO B1946+770 QSO 19 44 54.8532392016 +77 05 52.673448048     15.8     ~ 151 0
23 QSO B2059-360 QSO 21 02 44.6068720464 -35 53 07.081042308   19.18 18.62     ~ 55 0
24 LBQS 2206-1958A QSO 22 08 52.0729138920 -19 43 59.866776948   17.49 17.33     ~ 213 0
25 QSO B2206-1959 QSO 22 09 00.6950774976 -19 44 19.743416484     18.65     ~ 83 0
26 QSO J2215-1611 QSO 22 15 27.2920172928 -16 11 33.057278052     18.10     ~ 47 0
27 KODIAQ J223619+132620 QSO 22 36 19.1931471480 +13 26 20.317350876   19.15 18.69     ~ 110 0
28 QSO J2246-6015 QSO 22 47 08.9258659440 -60 15 45.299400480           ~ 66 0
29 QSO B2343+125 QSO 23 46 28.200 +12 49 00.00     17.5     ~ 133 2
30 QSO B2344+125 QSO 23 46 32.80 +12 45 40.0     17.0     ~ 83 1
31 QSO B2348-147 BLL 23 51 29.8153792680 -14 27 56.840819544     16.9     ~ 76 1

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2023.01.31-07:48:25

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