J/MNRAS/435/482 DLA system from SDSS DR5 (Jorgenson+, 2013)
The Magellan uniform survey of damped Lyman α systems.
I. Cosmic metallicity evolution.
Jorgenson R.A., Murphy M.T., Thompson R.
<Mon. Not. R. Astron. Soc., 435, 482-501 (2013)>
=2013MNRAS.435..482J 2013MNRAS.435..482J
ADC_Keywords: QSOs ; Redshifts; Equivalent widths ; Abundances
Keywords: galaxies: evolution - galaxies: high-redshift - intergalactic medium -
quasars: absorption lines
Abstract:
We present the chemical abundance measurements of the first large,
medium-resolution, uniformly selected damped Lyman α system
(DLA) survey. The sample contains 99 DLAs towards 89 quasars selected
from the SDSS DR5 DLA sample in a uniform way. We analyse the
metallicities and kinematic diagnostics, including the velocity width
of 90 percent of the optical depth, ΔV90, and the equivalent
widths of the SiII λ1526 (Wλ1526), CIV λ1548 and
MgII λ2796 transitions. To avoid strong line-saturation effects
on the metallicities measured in medium-resolution spectra
(FWHM∼71km/s), we derived metallicities from metal transitions which
absorbed at most 35 percent of the quasar continuum flux. We find the
evolution in cosmic mean metallicity of the sample,
=(-0.04±0.13)z-(1.06±0.36), consistent with no evolution over
the redshift range z~[2.2, 4.4], but note that the majority of our
sample falls at z~[2.2, 3.5]. The apparent lack of metallicity
evolution with redshift is also seen in a lack of evolution in the
median ΔV90 and Wλ1526 values. While this result may
seem to conflict with other large surveys that have detected
significant metallicity evolution, such as Rafelski et al. who found
=(-0.22±0.03)z-(0.65±0.09) over z~[0, 5], several tests show
that these surveys are not inconsistent with our new result. However,
over the smaller redshift range covered by our uniformly selected
sample, the true evolution of the cosmic mean metallicity in DLAs may
be somewhat flatter than the Rafelski et al. (2012ApJ...755...89R 2012ApJ...755...89R,
Cat. J/ApJ/755/89) estimate.
Description:
Spectra were observed primarily during four observing runs during 2008
December and 2009 January, June and July with the MagE Spectrometer on
the Magellan II Clay telescope at Las Campanas Observatory.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 108 103 DLA (damped Lyman α) Sample
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See also:
J/other/PASA/19.455 : Damped Lyman alpha absorption of QSOs (Curran+, 2002)
J/MNRAS/346/1103 : Redshifts of damped Lyα absorbers (Peroux+, 2003)
J/MNRAS/354/L31 : SDSS DR2 QSO and DLA properties (Murphy+, 2004)
J/A+A/473/791 : CIV absorption in DLAs and sub-DLAs systems (Fox+, 2007)
J/MNRAS/392/998 : Damped Lymanα systems (Ellison+, 2009)
J/A+A/508/133 : DLA absorbers in z>4 QSOs (Guimaraes+, 2009)
J/A+A/566/A24 : Extremely strong DLA systems (Noterdaeme+, 2014)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Quasar Quasar name (JHHMM+DDMM)
12- 17 F6.4 --- zem [2.4/5.0] Emission redshift
19- 24 F6.4 --- zabs [2.2/4.4] Absorption redshift
26- 30 F5.2 [cm-2] logN(HI) HI column density
32- 35 F4.2 [cm-2] E_logN(HI) Error on HI (upper value)
37- 40 F4.2 [cm-2] e_logN(HI) Error on HI (lower value)
42- 44 I3 km/s DV90 Velocity width of 90% of the optical depth
46- 49 F4.2 0.1nm W1526 ?=- SiII 1526Å rest equivalent width (1)
51- 54 F4.2 0.1nm e_W1526 ? rms uncertainty on W1526
56- 59 F4.2 0.1nm W1548 ?=- CIV 1548Å rest equivalent width (1)
61- 64 F4.2 0.1nm e_W1548 ? rms uncertainty on W1548
66- 70 F5.2 [Sun] [M/H] Metallicity
72- 75 F4.2 [Sun] e_[M/H] rms uncertainty on [M/H]
77- 78 I2 --- n_[M/H] Flag describing metallicity measurement (2)
80- 84 F5.2 [Sun] [Fe/H] Iron abundance
86- 89 F4.2 [Sun] e_[Fe/H] rms uncertainty on [Fe/H]
91- 92 I2 --- n_[Fe/H] Flag describing Fe Measurement (3)
94 I1 --- Inst Instrument code (4)
96-100 I5 s texp Exposure time
102-108 A7 --- Prog VLT programme ID numbers (5)
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Note (1): No value indicates either no spectral coverage or severe blending
that precluded an equivalent width measurement.
Note (2): Flag describing the metallicity measurement as follows:
1 = Si measurement
2 = Zn measurement
4 = S measurement
13 = mix of limits
14 = Fe measurement + 0.3
15 = Fe Limit + 0.3
Note (3): Flag describing the Fe Measurement as follows:
1 = Fe abundance
2 = Fe lower limit
3 = Fe upper limit
4 = Ni abundance offset by -0.1
5 = Cr abundance offset by -0.2
6 = Al abundance
11 = Fe limits from a pair of transitions
13 = Limit from Fe+Ni
Note (4): Instrument Used as follows:
1 = MagE (FWHM∼71km/s)
2 = X-Shooter (FWHM∼59km/s)
3 = UVES (FWHM∼8km/s)
4 = HIRES (FWHM∼8km/s)
Note (5): VLT programme ID number as follows:
1 = 069.A-0613
2 = 071.A-0114
3 = 073.A-0653
4 = 074.A-0201
5 = 080.A-0014
6 = 080.A-0482
7 = 081.A-0334
8 = 080.A-0482
9 = 076.A-0376
10 = 067.A-0146
11 = 073.B-0787
12 = 067.A-0078
13 = 068.A-0600
14 = 072.A-0346
15 = 079.A-0404
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 16-Sep-2014