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J/MNRAS/392/998     Damped Lymanα systems               (Ellison+, 2009)

The kinematic signature of damped Lyman alpha systems: using the D-index to screen for high column density HI absorbers. Ellison S.L., Murphy M.T., Dessauges-Zavadsky M. <Mon. Not. R. Astron. Soc., 392, 998-1007 (2009)> =2009MNRAS.392..998E
ADC_Keywords: QSOs ; Redshifts ; Equivalent widths Keywords: galaxies: high redshift - quasars: absorption lines Abstract: Using a sample of 21 damped Lyman alpha systems (DLAs) and 35 sub-DLAs, we evaluate the D-index=[EW(Å)/Δv(km/s)]x1000 from high-resolution spectra of the MgII λ2796 profile. This sample represents an increase in the sub-DLA statistics by a factor of 4 over the original D-index sample. We investigate various techniques to define the velocity spread (Δv) of the MgII line to determine an optimal D-index for the identification of DLAs. The success rate of DLA identification is 50-55 per cent, depending on the velocity limits used, improving by a few per cent when the column density of FeII is included in the D-index calculation. We recommend the set of parameters that are judged to be most robust, have a combination of high DLA identification rate (57 per cent) and low DLA miss rate (6 per cent) and most cleanly separate the DLAs and sub-DLAs (Kolmogorov-Smirnov probability 0.5 per cent). These statistics demonstrate that the D-index is the most efficient technique for selecting low-redshift DLA candidates. Description: We selected sub-DLAs from the compilation of Rao et al. (2006, Cat. J/ApJ/636/610) for follow-up spectroscopy at high resolution, obtaining new echelle spectra of 13 quasi-stellar objects (QSOs) with 17 absorbers along their lines of sight. Nine of these QSOs were observed with UVES at the VLT and four with the High-Resolution Echelle Spectrograph (HIRES) at the Keck telescope. The observations and data reduction are described in detail in Dessauges-Zavadsky et al. (in preparation). File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table4.dat 72 56 *MgII 2796 equivalent widths (and errors) and dV for the 3 approaches used in this paper
Note on table4.dat: In all cases, only the central absorption component is considered.
See also: J/ApJ/636/610 : Damped Lyα systems at z<1.65 (Rao+, 2006) Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 10 A10 --- QSO QSO name 12- 16 F5.2 [cm-2] logNHI HI column density 18- 21 F4.2 [cm-2] e_logNHI rms uncertainty on logNHI 23- 26 F4.2 0.1nm EW(ew) Equivalent width at 90% EW 28- 31 F4.2 0.1nm e_EW(ew) rms uncertainty on EW(ew) 33- 38 F6.2 km/s DV(ew) Velocity spread (DeltaV) at 90% EW 40- 43 F4.2 km/s EW(vel) Equivalent width at 90% vel 45- 48 F4.2 km/s e_EW(vel) rms uncertainty on EW(vel) 50- 55 F6.2 km/s DV(vel) Velocity spread (DeltaV) at 90% of the velocity range 57- 60 F4.2 km/s EW(3s) Equivalent width at 3σ 62- 65 F4.2 km/s e_EW(3s) rms uncertainty on EW(3s) 67- 72 F6.2 km/s DV(3s) Velocity spread (DeltaV) at bounds set by 3σ absorption
History: From electronic version of the journal
(End) Patricia Vannier [CDS] 07-May-2009
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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