J/ApJ/679/239 Associated MgII absorbers (Vanden+, 2008)
Average properties of a large sample of zabs∼ zemAssociated Mg II absorption line systems. Vanden Berk D., Khare P., York D.G., Richards G.T., Lundgren B., Alsayyad Y., Kulkarni V.P., Subbarao M., Schneider D.P., Heckman T., Anderson S., Crotts A.P.S., Frieman J., Stoughton C., Lauroesch J.T., Hall P.B., Meiksin A., Steffing M., Vanlandingham J. <Astrophys. J., 679, 239-259 (2008)> =2008ApJ...679..239V
ADC_Keywords: QSOs ; Equivalent widths ; Redshifts ; Photometry, SDSS Keywords: dust, extinction - ISM: abundances - quasars: absorption lines Abstract: We studied a sample of 415 associated (zabs∼zem; relative velocity with respect to QSO in units of c, β<0.01) MgII absorption systems with 1.0≤zabs≤1.86, in the spectra of SDSS DR3 QSOs, to determine the dust content and ionization state in the absorbers. We also compared these properties to those of a similarly selected sample of 809 intervening systems (β>0.01), so as to understand their origin. Normalized, composite spectra were derived for absorption line measurements, for the full sample and for several subsamples, chosen on the basis of the line strengths and other absorber and QSO properties. From these, and from the equivalent widths in individual spectra, we conclude that the associated MgII absorbers have higher ionization (higher ratios of the strengths of CIV and MgII lines), than the intervening absorbers. The ionization decreases with increasing β. Average extinction curves were obtained for the subsamples by comparing their geometric mean QSO spectra with those of matching (in zem and i magnitude) samples of QSOs without absorption lines. There is clear evidence for SMC-like dust attenuation in these systems; the 2175Å absorption feature is absent. The extinction is almost twice that observed in intervening systems. We reconfirm that QSOs with nonzero FIRST radio flux are intrinsically redder than the QSOs with no detection in the FIRST survey. Description: The absorption-line system sample used here was selected from the SDSS DR3 absorption-line catalog compiled by York et al. (2005pgqa.conf...58Y, 2006MNRAS.367..945Y). The SDSS is an imaging and spectroscopic survey carried out from Apache Point Observatory, near Sunspot, New Mexico, using a 2.5m telescope. Candidate QSOs are color-selected from five-color scans with a CCD camera. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table5.dat 87 415 The full absorber and matching non-absorber samples table6.dat 122 415 Equivalent widths of chosen lines
See also: II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009) J/ApJ/639/766 : SDSS-DR3 strong MgII absorbers (Prochter+, 2006) J/ApJS/165/1 : BAL QSOs from SDSS DR3 (Trump+, 2006) J/MNRAS/371/495 : Catalogue of 1806 MgII absorbers from SDSS DR3 (Bouche+, 2006) J/MNRAS/354/L25 : MgII absorbers in SDSS QSOs (Bouche+, 2004) J/A+A/410/33 : MgII/FeII absorbers in 2dF-quasar survey (Menard+, 2003) Byte-by-byte Description of file: table5.dat
Bytes Format Units Label Explanations
1- 4 I4 --- Plate Absorber plate number 6- 8 I3 --- Fiber Absorber fiber number 10- 14 I5 d MJD Absorber Modified Julian Date 16- 21 F6.4 --- zem(A) Absorber emission line redshift 23- 29 F7.4 mag Dg-i(A) Absorber Δ(g-i) (1) 31- 36 F6.4 --- zab(A) Absorber absorption line redshift 38- 43 F6.3 mag imag(A) Absorber SDSS i band magnitude 45- 50 F6.3 --- beta(A) Absorber β value (2) 52- 55 I4 --- Plate2 Non-absorber plate number 57- 59 I3 --- Fiber2 Non-absorber fiber number 61- 65 I5 d MJD2 Non-absorber Modified Julian Date 67- 72 F6.4 --- zem(N) Non-absorber emission line redshift 74- 80 F7.4 mag Dg-i(N) Non-absorber Δ(g-i) (1) 82- 87 F6.3 mag imag(N) Non-absorber SDSS i band magnitude
Note (1): Defined as the difference between the (g-i) color of a QSO and the median value of (g-i) of all other verified SDSS QSOs with nearly the same redshift (Richards et al., 2003AJ....126.1131R). Note (2): β = ((1+zem)2-(1+zabs)2)/((1+zem)2+(1+zabs)2).
Byte-by-byte Description of file: table6.dat
Bytes Format Units Label Explanations
1- 4 I4 --- Plate Absorber plate number 6- 8 I3 --- Fiber Absorber fiber number 10- 14 I5 d MJD Absorber Modified Julian Date 16- 20 F5.2 0.1nm AlII ?=-1.0 Equivalent width of AlII (1670Å) (1) 22- 26 F5.2 0.1nm e_AlII ?=-1.0 The 1σ error in AlII (1) 28- 32 F5.2 0.1nm CIVa ?=-1.0 Equivalent width of CIV (1548Å) (1) 34- 38 F5.2 0.1nm e_CIVa ?=-1.0 The 1σ error in CIVa (1) 40- 44 F5.2 0.1nm CIVb ?=-1.0 Equivalent width of CIV (1550Å) (1) 46- 50 F5.2 0.1nm e_CIVb ?=-1.0 The 1σ error in CIVb (1) 52- 56 F5.2 0.1nm MgI ?=-1.0 Equivalent width of MgI (2852Å) (1) 58- 62 F5.2 0.1nm e_MgI ?=-1.0 The 1σ error in MgI (1) 64- 68 F5.2 0.1nm MgIIa ?=-1.0 Equivalent width of MgII (2796Å) (1) 70- 74 F5.2 0.1nm e_MgIIa ?=-1.0 The 1σ error in MgIIa (1) 76- 80 F5.2 0.1nm MgIIb ?=-1.0 Equivalent width of MgII (2803Å) (1) 82- 86 F5.2 0.1nm e_MgIIb ?=-1.0 The 1σ error in MgIIb (1) 88- 92 F5.2 0.1nm SiIVa ?=-1.0 Equivalent width of SiIV (1396Å) (1) 94- 98 F5.2 0.1nm e_SiIVa ?=-1.0 The 1σ error in SiIVa (1) 100-104 F5.2 0.1nm SiIVb ?=-1.0 Equivalent width of SiIV (1403Å) (1) 106-110 F5.2 0.1nm e_SiIVb ?=-1.0 The 1σ error in SiIVb (1) 112-116 F5.2 0.1nm FeII ?=-1.0 Equivalent width of FeII (2382Å) (1) 118-122 F5.2 0.1nm e_FeII ?=-1.0 The 1σ error in FeII (1)
Note (1): In the absorber rest frame and in units of Angstroms. Equivalent widths and error values of "-1.0" indicate that the line was not detected and the line was not covered by the SDSS spectrum, respectively.
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 01-Oct-2010
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