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J/ApJ/524/536   Nearby Lyα quasar absorbers        (Impey+, 1999)

A study of Lyα quasar absorbers in the nearby universe Impey C.D., Petry C.E., Flint K.P. <Astrophys. J. 524, 536 (1999)> =1999ApJ...524..536I
ADC_Keywords: QSOs ; Spectroscopy Mission_Name: HST Keywords: galaxies: halos - intergalactic medium - large-scale structure of universe - quasars: absorption lines Abstract: Spectroscopy of 10 quasars obtained with the Goddard High Resolution Spectrograph (GHRS) of the Hubble Space Telescope (HST) is presented. In the 10 sight lines, we detect 357 absorption lines above a significance level of 3σ and 272 lines above a significance level of 4.5σ. Automated software is used to detect and identify the lines, almost all of which are unresolved at the GHRS G140L resolution of 200km/s. After identifying Galactic lines, intervening metal lines, and higher order Lyman lines, we are left with 139 Lyα absorbers in the redshift range 0<z<0.22 (lines within 900km/s of geocoronal Lyα are not selected). These diffuse hydrogen absorbers have column densities that are mostly in the range 1013-1015cm-2 for an assumed Doppler parameter of 30km/s. The number density of lines above a rest equivalent width of 0.24Å, dN/dz=38.3±5.3, agrees well with the measurement from the Quasar Absorption-Line Key Project. There is marginal evidence for cosmic variance in the number of absorbers detected among the 10 sight lines. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 132 355 Absorption-Line measurements & identifications
See also: VII/23 : A catalogue of absorption lines in QSO spectra J/ApJS/77/203 : QSO absorption systems (Junkkarinen+ 1991) J/ApJS/97/1 : HST Quasar Absorption Line Key Project. X. (Lockman+ 1995) Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 13 A13 --- Name QSO name 15- 18 F4.2 --- z QSO redshift 21- 22 I2 --- Number Absorption line number 25- 31 F7.2 0.1nm Wave Observed vacuum heliocentric line wavelength in Angstroms 34- 37 F4.2 0.1nm e_Wave Error in Wave in Angstroms 39 A1 --- f_Wave [h] Flag on Wave (1) 41- 45 F5.3 0.1nm EqWidth Equivalent width in Angstroms 48- 52 F5.3 0.1nm e_EqWidth Error in EqWidth in Angstroms 57- 60 F4.2 0.1nm FWHM Full Width Half Maximum in Angstroms (2) 63- 66 F4.2 0.1nm e_FWHM Error in the FWHM in Angstroms 69- 73 F5.2 --- Chi2 The Χ2 of the line fit 79- 83 F5.2 --- Signif Significance of the line width (3) 86- 91 F6.2 --- SignifL Significance of the line width (4) 93 A1 --- f_SignifL [i] Flag on SignifL (5) 95-101 F7.5 --- zAbsorp ? Redshift of the absorption system 103-113 A11 --- ID Line identification 115 A1 --- f_ID [*] Indicates excited transitions 116 A1 --- n_ID [fg] Note on ID (6) 118-121 I4 0.1nm RWave ? Rest wavelength of line 122 A1 --- f_RWave [ab] Indicates one of the two strongest transitions of the N I 1200 angstrom triplet 127-131 F5.2 0.1nm DWave ? Wavelength residual in Angstroms (7)
Note (1): On wing of damped Lyα; Wave is very uncertain Note (2): Lines with a value of 0.80±0.00 were fit with the FWHM set to the minimum allowed value. Note (3): Significance of the line defined as EqWidth/σW, where σW is the error in the measured equivalent width. Note (4): Significance of the line defined as EqWidth/σlim, where σlim is the 1σ (observed) limiting equivalent width. Note (5): Based on a single comparison with a higher resolution spectrum of 3C 273, a significant fraction of lines with 3.0 < SignifL < 4.5 may be false detections. Note (6): f = Alternately identified as Si II 1304 at z = 0.0000 with residual 0.45 Angstroms. g = Alternately identified as Si II 1190 at z = 0.1419 with residual -0.53 Angstroms. Note (7): Defined as (λmeasured - λpredicted)
History: From ApJ electronic edition
(End) Greg Schwarz [AAS] 13-Mar-2000
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