J/MNRAS/435/482 DLA system from SDSS DR5 (Jorgenson+, 2013) ================================================================================ The Magellan uniform survey of damped Lyman {alpha} systems. I. Cosmic metallicity evolution. Jorgenson R.A., Murphy M.T., Thompson R. =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 {alpha} 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, {Delta}V_90_, and the equivalent widths of the SiII {lambda}1526 (W}{lambda}1526), CIV {lambda}1548 and MgII {lambda}2796 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 {Delta}V_90_ and W{lambda}1526 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, 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: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 108 103 DLA (damped Lyman {alpha}) Sample -------------------------------------------------------------------------------- See also: J/other/PASA/19.455 : Damped Lyman alpha absorption of QSOs (Curran+, 2002) J/MNRAS/346/1103 : Redshifts of damped Ly{alpha} 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 Lyman{alpha} 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 -------------------------------------------------------------------------------- Bytes Format Units Label Explanations -------------------------------------------------------------------------------- 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 1526{AA} rest equivalent width (1) 51- 54 F4.2 0.1nm e_W1526 ? rms uncertainty on W1526 56- 59 F4.2 0.1nm W1548 ?=- CIV 1548{AA} 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) -------------------------------------------------------------------------------- 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 -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Patricia Vannier [CDS] 16-Sep-2014