J/MNRAS/444/744 EUADP sample. [N/α] distribution (Zafar+, 2014)
The ESO UVES advanced data products quasar sample.
III. Evidence of bimodality in the [N/α] distribution.
Zafar T., Centurion M., Peroux C., Molaro P., D'Odorico V., Vladilo G.,
Popping A.
<Mon. Not. R. Astron. Soc., 444, 744-756 (2014)>
=2014MNRAS.444..744Z 2014MNRAS.444..744Z
ADC_Keywords: QSOs ; Abundances
Keywords: galaxies: abundances - galaxies: evolution - galaxies: formation -
galaxies: ISM - quasars: absorption lines
Abstract:
We report here a study of nitrogen and α-capture element (O, S,
and Si) abundances in 18 damped Lyα absorbers (DLAs) and
sub-DLAs drawn from the European Southern Observatory's Ultraviolet
Visual Echelle Spectrograph (ESO-UVES) Advanced Data Products (EUADP)
data base. We report nine new measurements, five upper and four lower
limits of nitrogen that when compiled with available nitrogen
measurements from the literature makes a sample of 108 systems. The
extended sample presented here confirms the [N/α] bimodal
behaviour suggested in previous studies. Three-quarter of the systems
show <[N/α]≥-0.85 (±0.20dex) and one-quarter of the
systems show that ratios are clustered at <[N/α]≥-1.41
(±0.14dex). The high [N/α] plateau is consistent with the Hii
regions of dwarf irregular and blue compact dwarf galaxies although
extended to lower metallicities and could be interpreted as the result
of a primary nitrogen production by intermediate mass stars. The low
[N/α] values are the lowest ever observed in any astrophysical
site. In spite of this fact, even lower values could be measured with
the present instrumentation, but we do not find them below
[N/α]~-1.7. This suggests the presence of a floor in [N/α]
abundances, which along with the lockstep increase of N and Si may
indicate a primary nitrogen production from fast rotating, massive
stars in relatively young or unevolved systems.
Description:
The new NI measurements are from a sample of 250 quasar spectra
observed with the Ultraviolet Visual Echelle Spectrograph (UVES)
mounted on the European Southern Observatory's (ESO), Very Large
Telescope (VLT).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table12.dat 123 108 N and α-element abundance measurements
in DLAs and sub-DLAs
refs.dat 85 50 References
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See also:
J/A+A/556/A141 : ESO-UVES Advanced Data Products (EUADP) sample (Zafar+, 2013)
Byte-by-byte Description of file: table12.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- QSO QSO name
15 A1 --- n_QSO [*+] New estimate, several components (1)
18- 22 F5.3 --- zabs [0.1/4.5] Absorption redshift
24- 28 F5.2 [cm-2] logNHI [19.6/21.8] HI column density
30- 33 F4.2 [cm-2] e_logNHI [0.01/0.4] rms uncertainty on logNHI
35- 36 A2 --- l_logNNI [<≥ ] Limit flag on logNNI
37- 41 F5.2 [cm-2] logNNI [12/16] NI column density
43- 46 F4.2 [cm-2] e_logNNI [0.01/0.4]? rms uncertainty on logNNI
48- 49 A2 --- l_[N/H] [<≥ ] Limit flag on [N/H]
50- 54 F5.2 [Sun] [N/H] [-4.2/-0.2] Abundance [N/H]
56- 59 F4.2 [Sun] e_[N/H] [0.03/0.4]? rms uncertainty on [N/H]
61- 62 A2 --- l_[Si/H] [<≥ ] Limit flag on [Si/H]
63- 67 F5.2 [Sun] [Si/H] [-3.1/0.1]?=- Abundance [Si/H]
69- 72 F4.2 [Sun] e_[Si/H] [0.01/0.4]? rms uncertainty on [Si/H]
74- 75 A2 --- l_[N/Si] [<≥ ] Limit flag on [N/Si]
76- 80 F5.2 [Sun] [N/Si] [-1.7/0.7]?=- Abundance [N/Si]
82- 85 F4.2 [Sun] e_[N/Si] [0.02/0.4]? rms uncertainty on [N/Si]
87- 88 A2 --- aEl α-element used for the determination of
[a/H] and [N/a] ratios (O, S or Si)
90- 91 A2 --- l_[a/H] [<≥ ] Limit flag on [a/H]
92- 96 F5.2 [Sun] [a/H] [-2.8/0.2] Abundance [α/H]
98-101 F4.2 [Sun] e_[a/H] [0.02/0.4]? rms uncertainty on [a/H]
103-104 A2 --- l_[N/a] [<≥ ] Limit flag on [N/a]
105-109 F5.2 [Sun] [N/a] [-1.7/0.1] Abundance [N/α]
111-114 F4.2 [Sun] e_[N/a] [0.01/0.35]? rms uncertainty on [N/a]
116-123 A8 --- Refs References, in refs.dat file
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Note (1): Notes as follows:
* = new estimates presented in this work
+ = the column densities are provided for the component seen in NI.
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Ref Reference number
4- 22 A19 --- BibCode BibCode
24- 48 A25 --- aut Author's name
50- 85 A36 --- Com Comments
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History:
From electronic version of the journal
References:
Zafar et al., Paper I 2013A&A...556A.140Z 2013A&A...556A.140Z
Zafar et al., Paper II 2013A&A...556A.141Z 2013A&A...556A.141Z, Cat. J/A+A/556/A141
Zafar et al., Paper IV 2014MNRAS.445.2093Z 2014MNRAS.445.2093Z
(End) Patricia Vannier [CDS] 23-Apr-2015