Access to Astronomical Catalogues

← Click to display the menu
J/ApJ/480/568       RK photometry in 3C 336 field (Steidel+ 1997)

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)
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 (zem=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 (LK≥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-α system at zabs=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-1kpc, 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-1kpc of the QSO sight line that do not produce detectable metal-line absorption. There are no bright galaxies (L>0.1LK) within 50h-1kpc that do not produce detectable metal lines (of Mg II λλ2796, 2803 and/or C IV λλ1548, 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: ---------------------------------------------------------- RA (2000) DE Designation(s) ---------------------------------------------------------- 16 24 39.0 +23 45 13 3C 336 ---------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table4 52 156 *Objects in the field of 3C 336
Note to table4: Only Objects within 50" of the QSO are included. Byte-by-byte Description of file: table4
Bytes Format Units Label Explanations
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
Note (1): In the AB-magnitude system, any object with a flat spectrum (F_ν prop. to ν0) has the same magnitude, independent of passband: mAB=-2.5log(f_ν) - 48.59 Rmag in AD system corresponds to the effective wavelength of 6930Å
History: Prepared via OCR at CDS.
(End) James Marcout, Patricia Bauer [CDS] 08-Oct-1997
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

catalogue service