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J/ApJ/480/568 RK photometry in 3C 336 field (Steidel+ 1997)
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Quasar absorbing galaxies at z<=1.
I. Deep imaging and spectroscopy in the field of 3C 336.
Steidel C.C., Dickinson M., Meyer D.M., Adelberger K.L., Sembach K.R.
<Astrophys. J. 480, 568 (1997)>
=1997ApJ...480..568S (SIMBAD/NED BibCode)
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ADC_Keywords: QSOs ; Photometry ; Redshifts
Mission_Name: HST
Keywords: galaxies: distances and redshifts - quasars: absorption lines -
quasars: individual (3C 336)
Abstract:
We present very deep WFPC2 images and FOS spectroscopy from the Hubble
Space Telescope (HST) together with numerous supporting ground-based
observations of the field of the quasar 3C 336 (z_em_=0.927). The
observations are designed to investigate the nature of galaxies
producing metal-line absorption systems in the spectrum of the QSO.
Along a single line of sight, we find at least six metal-line
absorption systems (of which three are newly discovered) ranging in
redshift from 0.317 to 0.892. Through an extensive program of optical
and IR imaging, QSO spectroscopy, and faint galaxy spectroscopy, we
have identified five of the six metal-line absorption systems with
luminous (L_K_>=0.1L^*^_K_) galaxies. These have morphologies ranging
from very late-type spiral to S0, and they exhibit a wide range of
inclination and position angles with respect to the QSO sight line.
The only unidentified absorber, despite our intensive search, is a
damped Lyman-{alpha} system at z_abs_=0.656. Analysis of the
absorption spectrum suggests that the metal abundances ([Fe/H]=-1.2)
in this system are similar to those in damped systems at z~2 and to
the two other damped systems for which abundances have been determined
at z<1. The absorption line system must either be associated with an
underluminous, late-type spiral galaxy, which we find at a projected
disk impact parameter of ~120h^-1^kpc, or with an as yet unseen,
extremely faint galaxy (L<0.05L^*^_K_) near the QSO sight line that
eludes detection despite our deep HST and high-resolution ground-based
near-IR images. We have found no examples of intrinsically faint
galaxies (L<0.1L^*^) at small impact parameters that might have been
missed as absorber candidates in our previous ground-based imaging and
spectroscopic programs on Mg II absorbing galaxies. We have, however,
identified several intrinsically faint galaxies within ~50h^-1^kpc of
the QSO sight line that do not produce detectable metal-line
absorption. There are no bright galaxies (L>0.1L_K_) within 50h^-1^kpc
that do not produce detectable metal lines (of Mg II
{lambda}{lambda}2796, 2803 and/or C IV {lambda}{lambda}1548, 1550) in
the QSO spectrum. All of these results generally support the
inferences we have previously reached from a larger survey for
absorption-selected galaxies at z<1. There are several other galaxies
with redshifts near that of 3C 336, suggesting that the QSO is
situated in an overdense region, perhaps a galaxy cluster. Previously
published reports of a cluster around 3C 336 were largely misled by
the presence of many foreground galaxies seen in projection near the
QSO. It is possible that a reported measurement of weak shear
gravitational lensing in this field may be produced by the QSO cluster
itself, since there appear to be no other groups or clusters in the
foreground. We find no evidence for a normal, bright QSO host galaxy,
although there are several faint objects very close to the quasar and
at similar redshift that might either be companions or part of a
disorganized QSO host.
Objects:
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RA (2000) DE Designation(s)
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16 24 39.0 +23 45 13 3C 336
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4 52 156 *Objects in the field of 3C 336
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Note on table4: Only Objects within 50" of the QSO are included.
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Byte-by-byte Description of file: table4
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Bytes Format Units Label Explanations
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1- 3 I3 --- ID Identification number
5- 10 F6.2 arcsec oRA Offset in right ascension from ID 1 (3C 336)
12- 17 F6.2 arcsec oDE Offset in declination from ID 1
19- 23 F5.2 arcsec oPA Offset in position angle from ID 1
25 A1 --- l_Rmag Limit flag on Rmag
26- 30 F5.2 mag Rmag R magnitude in AB system (1)
33 A1 --- l_Kmag Limit flag on Kmag
34- 38 F5.2 mag Kmag K magnitude (in usual system)
40 A1 --- l_R-K Limit flag on R-K
41- 44 F4.2 mag R-K R-K colour index in AB system (1)
47- 51 F5.3 --- z ? Redshift
52 A1 --- n_z [s] s: star
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Note (1): In the AB-magnitude system, any object with a flat spectrum
(F_{nu} prop. to {nu}^0^) has the same magnitude,
independent of passband: m_AB_=-2.5log(f_{nu}) - 48.59
Rmag in AD system corresponds to the effective wavelength of 6930{AA}
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History: Prepared via OCR at CDS.
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(End) James Marcout, Patricia Bauer [CDS] 08-Oct-1997