COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses VI. Redshift of the lensing galaxy in seven gravitationally lensed quasars

Abstract

Aims: The knowledge of the redshift of a lensing galaxy that produces multiple images of a background quasar is essential to any subsequent modeling, whether related to the determination of the Hubble constant H_0 or to the mass profile of the lensing galaxy. We present the results of our ongoing spectroscopic observations of gravitationally lensed quasars in order to measure the redshift of their lensing galaxies. We report on the determination of the lens redshift in seven gravitationally lensed systems. Methods: Our deep VLT/FORS1 spectra are spatially deconvolved in order to separate the spectrum of the lensing galaxies from the glare of the much brighter quasar images. Our observing strategy involves observations in Multi-Object-Spectroscopy (MOS) mode which allows the simultaneous observation of the target and of several crucial PSF and flux calibration stars. The advantage of this method over traditional long-slit observations is that it allows a much more reliable extraction and flux calibration of the spectra. Results: We obtain the first reliable spectra of the lensing galaxies in six lensed quasars: FBQ 0951+2635 (z=0.260), BRI 0952-0115 (z=0.632), HE 2149-2745 (z=0.603), Q 0142-100 (z=0.491), SDSS J0246-0825 (z=0.723), and SDSS J0806+2006 (z=0.573). The last 3 redshifts also correspond to the MgII doublet seen in absorption in the quasar spectra at the lens redshift. Our spectroscopic redshifts of HE 2149-2745 and FBQ 0951+2635 are higher than previously reported, which means that H_0 estimates from these two systems must be revised to higher values. Finally, we reanalyse our spectra of Q 1355-2257 and find MgII in absorption at z=0.702, confirming our previous redshift estimate. The spectra of all lenses are typical of early-type galaxies.

arXiv comment7 pages, 13 figures, accepted for publication in A&A

References in corpus (20)

• Deconvolution with correct sampling
• The Fundamental Plane of Gravitational Lens Galaxies and The Evolution of Early-Type Galaxies in Low Density Environments
• What Do Gravitational Lens Time Delays Measure?
• A Spectroscopic Study of the Environments of Gravitational Lens Galaxies
• An Optical Time-Delay for the Lensed BAL Quasar HE2149-2745
• COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses I. How to sample the light curves of gravitationally lensed quasars to measure accurate time delays
• WFI J2026-4536 and WFI J2033-4723: Two New Quadruple Gravitational Lenses
• The Hubble time inferred from 10 time-delay lenses
• COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses III. Redshift of the lensing galaxy in eight gravitationally lensed quasars
• The First FIRST Gravitationally Lensed Quasar: FBQ 0951+2635
• An optical time delay for the double gravitational lens system FBQ 0951+2635
• COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses II. SDSS J0924+0219: the redshift of the lensing galaxy, the quasar spectral variability and the Einstein rings
• First Results from a Photometric Survey of Strong Gravitational Lens Environments
• COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses V. The time delay in SDSS J1650+4251
• Spectroscopic Redshifts for Seven Lens Galaxies
• SDSS J0246-0825: A New Gravitationally Lensed Quasar from the Sloan Digital Sky Survey
• A method for spatial deconvolution of spectra
• Gravitational Lens Time Delays in CDM
• SDSS J0806+2006 and SDSS J1353+1138: Two New Gravitationally Lensed Quasars from the Sloan Digital Sky Survey
• A search for clusters and groups of galaxies on the line of sight towards 8 lensed quasars

Cited by in corpus (47)

• Gravitational Lens Time Delays: A Statistical Assessment of Lens Model Dependences and Implications for the Global Hubble Constant
• The Sloan Digital Sky Survey Quasar Lens Search. V. Final Catalog from the Seventh Data Release
• COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses XIII: Time delays and 9-yr optical monitoring of the lensed quasar RX J1131-1231
• The Microlensing Properties of a Sample of 87 Lensed Quasars
• Microlensing of the broad line region in 17 lensed quasars
• COSMOGRAIL XIX: Time delays in 18 strongly lensed quasars from 15 years of optical monitoring
• The Sloan Digital Sky Survey Quasar Lens Search. III. Constraints on Dark Energy from the Third Data Release Quasar Lens Catalog
• The Sloan Digital Sky Survey Quasar Lens Search. VI. Constraints on Dark Energy and the Evolution of Massive Galaxies
• Survey of Gravitationally-lensed Objects in HSC Imaging (SuGOHI). II. Environments and Line-of-Sight Structure of Strong Gravitational Lens Galaxies to z ~ 0.8
• Galaxy Number Counts and Implications for Strong Lensing
• A Study of Gravitational Lens Chromaticity using Ground-based Narrow Band Photometry
• Constraints on cosmological models from lens redshift data
• How robust are the constraints on cosmology and galaxy evolution from the lens-redshift test?
• The Sloan Digital Sky Survey Quasar Lens Search. IV. Statistical Lens Sample from the Fifth Data Release
• A Study of Gravitational Lens Chromaticity with the Hubble Space Telescope
• Lens Galaxy Properties of SBS1520+530: Insights from Keck Spectroscopy and AO Imaging
• Resolved [CII] emission in a lensed quasar at z=4.4
• Origin of Chromatic Features in Multiple Quasars -Variability, Dust, or Microlensing -
• Five New High-Redshift Quasar Lenses from the Sloan Digital Sky Survey
• Differential X-ray Absorption and Dust-To-Gas Ratios of the Lens Galaxies SBS0909+523, FBQS0951+2635, and B1152+199
• Probing the Broad Line Region and the Accretion Disk in the Lensed Quasars HE0435-1223, WFI2033-4723, and HE2149-2745 using Gravitational Microlensing
• Toward an internally consistent astronomical distance scale
• Microlensing and Intrinsic Variability of the Broad Emission Lines of Lensed Quasars
• H0LiCOW VI. Testing the fidelity of lensed quasar host galaxy reconstruction
• A Spectroscopic Survey of the Fields of 28 Strong Gravitational Lenses: The Redshift Catalog
• Resolving the baryon-fraction profile in lensing galaxies
• A new parameter space study of cosmological microlensing
• Microlensing of the broad emission lines in 27 gravitationally lensed quasars. Broad line region structure and kinematics
• New database for a sample of optically bright lensed quasars in the northern hemisphere
• Testing the Evolution of the Correlations between Supermassive Black Holes and their Host Galaxies using Eight Strongly Lensed Quasars
• Probing Structure in Cold Gas at $z\lesssim 1$ with Gravitationally Lensed Quasar Sight Lines
• Time delay between images of the lensed quasar UM673
• Deep optical spectroscopy of extended Lyman alpha emission around three radio-quiet z=4.5 quasars
• A sharp look at the gravitationally lensed quasar SDSS J0806+2006 with Laser Guide Star Adaptive Optics
• Precision cosmology with time delay lenses: high resolution imaging requirements
• A Spectroscopic Survey of the Fields of 28 Strong Gravitational Lenses: Implications for $H_0$
• MiNDSTEp differential photometry of the gravitationally lensed quasars WFI2033-4723 and HE0047-1756: Microlensing and a new time delay
• Microlensing variability in FBQ 0951+2635: short-timescale events or a long-timescale fluctuation?
• Slit and integral-field optical spectroscopy of the enigmatic quasar HE0450-2958
• Strongly Lensed Jets, Time Delays, and the Value of H0
• Galaxy Clusters in the Line of Sight to Background Quasars - III Multi-Object Spectroscopy
• Long-term monitoring, time delay and microlensing in the gravitational lens system Q0142-100
• Exploring the environment, magnetic fields, and feedback effects of massive high-redshift galaxies with [CII]
• New near-infrared observations and lens-model constraints for UM673
• FBQ 0951+2635: time delay and structure of the main lensing galaxy
• Improving the light curves of gravitationally lensed quasars with Gaia proper motion data
• Primordial black holes in the main lensing galaxy of FBQ 0951+2635