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J/AJ/106/848 QSO MgII absorption line systems (Drinkwater+, 1993)
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On the nature of Mg II absorption line systems in quasars
Drinkwater M.J., Webster R.L., Thomas P.A.
<Astron. J. 106, 848 (1993)>
=1993AJ....106..848D (SIMBAD/NED Reference)
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ADC_Keywords: QSOs; Photometry, infrared; Combined data
Abstract:
The results of a large R-band imaging survey of 71 bright (m(V)<18)
quasars are presented. The quasars were chosen from published samples
which have intermediate resolution optical spectroscopy available, so
the presence of low redshift Mg II absorption lines can be determined.
We have searched our data for galaxies close to the line-of-sight to
the quasars, which we might be able to identify with the absorption
systems. We find a high coincidence between galaxies very near the
line-of-sight and quasars showing absorption systems in their spectra,
a result consistent with other studies. These galaxies have a mean
luminosity of 0.5L_star_ (assuming they lie at the absorption
redshift). The distribution of impact parameters between the galaxies
and the quasars extends with a flat distribution to large radii
(>30h^-1^kpc). This suggests that the absorption systems may not be
gravitationally bound to the observed galaxies, but may be part of
larger extended systems. We also find a significant number of galaxies
near the line-of-sight to the quasar where no absorption is seen in the
quasar spectrum. The selection of our quasars is unbiased with respect
to galaxies near the line-of-sight, so we can compare the observed
number of absorption systems to that predicted by a simple model with a
constant covering factor in Mg II absorbing gas within a maximum radius
of each detected galaxy. The model is consistent with a covering
factor of unity, but allowing for incompleteness in the detection of
galaxies, the covering factor is less than unity. The redshifts of the
galaxies are required to confirm this result.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 118 71 Quasars observed
table3a.dat 28 70 Quasar parameters
table3b.dat 52 399 Catalogue of quasar companions
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- QSO Quasar name
10- 12 A3 --- Type [RXCO ] Detection technique (1)
14- 15 I2 h RAh Right ascension 1950.0
17- 18 I2 min RAm Right ascension 1950.0
20- 24 F5.2 s RAs Right ascension 1950.0
26 A1 --- DE- Declination sign
27- 28 I2 deg DEd Declination 1950.0
30- 31 I2 arcmin DEm Declination 1950.0
33- 36 F4.1 arcsec DEs Declination 1950.0
38- 42 F5.2 mag Vmag Quasar V magnitude
44- 48 F5.3 --- z Quasar redshift (Data in bytes 1-48 taken from
Hewitt & Burbidge 1987, ApJS, 63, 1, and
Hewitt & Burbidge 1989, ApJS, 69, 1)
50- 53 F4.2 --- z1 Minimum redshift at which Mg II might be
observed in the published spectra
55- 58 F4.2 --- z2 Maximum redshift at which Mg II might be
observed in the published spectra
60- 65 F6.4 --- zab1 []? Redshift of any Mg II absorption systems
67- 72 F6.4 --- zab2 []? Redshift of any Mg II absorption systems
74- 82 A9 --- r_z Reference for the published spectra,
parentheses signifying a non-detection (2)
84- 91 A8 "DD/MM/YY" Date Date observed (UT)
93- 96 I4 s Epx.T Exposure time
98-101 F4.2 arcsec FWHM FWHM seeing
103-107 F5.2 mag Rmag Quasar R magnitude
109-110 A2 --- Note Photometry flag (3)
114-118 F5.2 mag Rmagl Limiting R magnitude of image (the magnitude
of the faintest object for which the formal
error in the magnitude was less than 0.2 mag)
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Note (1): C = color; O = spectral survey; R = radio; X = X-ray
Note (2): References for published spectra
|Number| W(rest) | Reference
| | 0.1nm
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| 1 | ~ 0.5 | Weyman, et al. 1979, ApJ, 234, 33
| 1a | ~ 0.8 | Weyman, et al. 1979, ApJ, 234, 33
| 2 | 0.6 | Young, et al. 1982, ApJS, 48, 455
| 3 | 0.5 | Foltz, et al. 1986, ApJ, 307, 504
| 4 | | Boulade, et al. 1987, in High Redshift and Primeval
| | | Galaxies, edited by J. Bergeron et al.
| | (Editions Frontieres, France), p. 349
| 5 | | Miller, et al. 1987, AJ, 94, 633
| 6 | ~ 0.4 | Tytler, et al. 1987, ApJS, 64, 667
| 7 | 0.3 | Sargent, et al. 1988, AJ, 334, 22
| 8 | ~ 0.5 | Bergeron & Boisse 1991, A&A, 243, 344
| 9 | 0.3 | Steidel & Sargent 1992, ApJS, 80, 1
|10 | 0.3 | Bechtold & Ellingson 1992, ApJ, 396, 20
|10a | 0.6 | Bechtold & Ellingson 1992, ApJ, 396, 20
Note (3): blank: photometric
X: not photometric
D: double image with magnitude from small DAOPHOT
e: no small DAOPHOT fitting was possible
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Byte-by-byte Description of file: table3a.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- QSO Quasar name
14- 18 F5.3 --- z Quasar redshift
20- 22 F3.1 arcsec Seeing Seeing
24- 28 F5.2 mag Mlim Magnitude limit
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Byte-by-byte Description of file: table3b.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- QSO Quasar name
15- 19 F5.1 arcsec dRA Rigth ascension offset from the quasar
21- 25 F5.1 arcsec dDE Declination offset from the quasar
28- 31 F4.1 arcsec Dist Distance from the quasar
33- 34 A2 --- cls [fgs ] Classification
(f: faint, g: galaxy, s: star)
36- 40 F5.2 mag Rmag Apparent R magnitude, m(R)
42- 45 F4.2 mag e_Rmag Formal photometry error in the magnitude
47- 52 F6.2 deg PA Position angle of the object with respect to
the quasar, measured anti-clockwise from North
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Origin: AAS CD-ROM series, Volume 1, 1993
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(End) Patricia Bauer [CDS] 07-Sep-1994