Q 1208 + 1011: the most distant multiply imaged quasar, or a binary?
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We present images taken with the Wide Field Planetary Camera (WFPC-2) on the Hubble Space Telescope of 43 quasars selected from the 3CR radio catalog. The redshift range of the targets is large --- 0.3 < z < 2. These data were taken in the course of a large program that imaged 267 3CR radio galaxies and quasars using the HST in snapshot mode. Each quasar was centered on the Planetary Camera (PC1) and was imaged through the F702W filter (bandpass similar to Cousins R), typically for 5 and 10 minutes. Our analysis suggests that the quasar fuzz contributes from <5% to nearly 100% in the most extreme case (about 20% being typical) of the total light from the quasar, with 16 of the quasars (~40%) being unresolved according to the analysis of their light profiles (with only 7 being considered unresolved determined by PSF subtraction of the quasar images). Most of the host galaxies show twisted, asymmetric, or distorted isophotes. About 1/4 of the quasar hosts have close (within a few arc seconds) companions seen in projection and about 1/10 show obvious signs of tidal interactions with a close companion. We find that these sources exhibit a tendency for the principal axes of the radio and optical emission to align similar but perhaps weaker than that observed for radio galaxies.
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The lens candidate RXJ 0921+4529 consists of two z_s=1.66 quasar separated by 6.93 with an H band magnitude difference of \Delta m=1.39. The lens appears to be a z_l=0.31 X-ray cluster, including a m_H=18.5 late-type galaxy lying between the quasar images. We detect an extended source overlapping the faint quasar but not the bright quasar. If this extended source is the host galaxy of the fainter quasar, then the system is a quasar binary rather than a gravitational lens.
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Very deep ESO/VLT FORS1 and ISAAC images, as well as HST NICMOS2 data are used to infer the nature of the quasar pair LBQS 1429-0053 A and B, either a binary quasar or a doubly-imaged lensed quasar. Direct search of a putative lensing galaxy is unsuccessful down to , , and . Moreover, no galaxy overdensity close to the quasar pair is found. A weak shear analysis of the FORS1 R-band 6.8´ 6.8´ field also fails at detecting any concentration of dark matter more massive than km s-1 and weakens the hypothesis of a dark lens. The only sign of a possible lens consists in a group of 5 objects having colors consistent with galaxies at , within a radius of 5´´ from the quasar pair. Considering this group as the lensing potential does not allow to reproduce the image position and flux ratio of LBQS 1429-0053 A and B. Our deep R-band image shows a blue, previously unknown, extended object at the position of LBQS 1429-0053 A, which is consistent with either being the lensed quasar A host, or being an intervening galaxy at lower redshift. Unless future very deep optical images demonstrate that this object is actually the lensed host of LBQS 1429-0053, we conclude that there is very little evidence for LBQS 1429-0053 being lensed. Therefore, we are led to declare LBQS 1429-0053 A and B a genuine binary quasar.
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view Abstract Citations (30) References (16) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Detection of Lens Candidates for the Double Quasar Q2345+007 Fischer, Philippe ; Tyson, J. Anthony ; Bernstein, Gary M. ; Guhathakurta, Puragra Abstract Luminous objects associated with the 7.06" separation double quasar Q2345+007 have, until now, escaped detection. In this Letter we present the results of the deepest known imaging of the region surrounding the quasar. The total exposure times were 47,600 seconds in B, (101 frames) and 32,160 seconds in A (82 frames). The frames came from CFHT, CTIO, and KPNO. We detect a B_J_ = 25.0 mag galaxy (B_J_ - R = 0.5 mag) in close proximity to the fainter QSO image, possibly at z = 1.49, given by several absorption features in the QSO spectra. Furthermore, there is a 2.9 σ enhancement in the number density of faint galaxies (24 <= B_J_ <= 28, B_J_ - R <= 1.5) near the quasar and another 3.1 σ enhancement farther away. These discoveries support the hypothesis that Q2345+007 is being lensed by one or more distant mass concentrations and may imply that compact "clusters" already exist at early epochs. We discuss several lens models for the system and the cosmological implications. Publication: The Astrophysical Journal Pub Date: August 1994 DOI: 10.1086/187475 arXiv: arXiv:astro-ph/9405062 Bibcode: 1994ApJ...431L..71F Keywords: Absorption Spectra; Dark Matter; Doppler-Fizeau Effect; Quasars; Space Density; Brownian Movements; Electrophotometers; Ellipticity; Galaxies; Time Measurement; Astrophysics; COSMOLOGY: DARK MATTER; GALAXIES: CLUSTERING; GALAXIES: QUASARS: INDIVIDUAL ALPHANUMERIC: Q2345; 007; COSMOLOGY: GRAVITATIONAL LENSING; Astrophysics E-Print: (uuencoded compressed postscript) full text sources arXiv | ADS | data products NED (3) SIMBAD (2)
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We report the discovery of a new two-image gravitational lens candidate. The system RX J0921+4529 contains two zs = 1.66 quasars separated by 693 with an H-band magnitude difference of Δm = 1.39. The HST NIC2 H-band images reveal an H = 18.2 spiral galaxy between the quasar images, which is probably a member of a zl = 0.32 X-ray cluster centered on the field. We detect an extended source near the fainter quasar image but not in the brighter image. If this extended source is the host galaxy of the fainter quasar, then the system is a binary quasar rather than a gravitational lens. VLA observations at 3.6 cm reveal emission from the lens galaxy at the flux level of 1 mJy and a marginal detection of the brighter quasar.
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We report the discovery of a pair of z = 4.25 quasars with a separation of 33''. The brighter of the two objects was identified as a high-redshift quasar candidate from Sloan Digital Sky Survey multicolor imaging data, and the redshift was measured from a spectrum obtained with the Hobby-Eberly Telescope. The slit orientation of this observation by chance included another quasar, approximately 1 mag fainter and having the same redshift as the target. This is the third serendipitous discovery of a z > 4 quasar. The differences in the relative strengths and profiles of the emission lines suggest that this is a quasar pair and not a gravitational lens. The two objects are likely to be physically associated; the projected physical separation is approximately 210 h kpc and the redshifts are identical to ≈0.01, implying a radial physical separation of 950 h kpc or less. The existence of this pair is strong circumstantial evidence that z ∼ 4 quasars are clustered.
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We present photometric and spectroscopic observations of two close quasar-quasar pairs found in the Large Bright Quasar Survey (LBQS). The two components of the 2153-2056 pair (z = 1.845, Δθ = 78, B = 17.9 and 21.3) have the same redshifts within the relatively large uncertainty, ΔvA-B = -1100 ± 1500 km s-1, of the observations. The quasars are most likely spatially coincident, although the possibility that the pair is the result of gravitational lensing cannot be ruled out. The two components of 1148+0055 (z = 1.879, B = 18.5 and z = 1.409, B = 21.1; Δθ = 39) have disjoint redshifts, and the pair has attracted some attention in the context of gravitational lensing following the independent discovery of the pair by Surdej and collaborators. Four close (Δθ ≤ 100) quasar-quasar pairs have now been discovered in the LBQS, and we discuss the probability of identifying pairs with disjoint redshifts and of locating spatially coincident pairs from the systematic investigation of the well-defined quasar catalog.
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We report the discovery of a binary quasar, MGC 2214+3550A,B, whose components have similar optical spectra at a redshift of z=0.88. The quasars are separated on the sky by 30 and have a magnitude difference of ΔmI=0.5 mag. The VLA radio map at 3.6 cm shows a single 47 mJy radio source with a core-jet morphology that is coincident with the brighter optical quasar A. Gravitational lensing is ruled out by the lack of radio emission from quasar B and the lack of any visible galaxies to act as the lens. We conclude that MGC 2214+3550A and B are physically associated. With a projected separation of 12.7 h−1 kpc (Ω0=1), MGC 2214+3550A,B is one of the smallest z>0.5 binary quasars.
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