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.

7 pages, 13 figures, accepted for publication in A&A

References in corpus (3)

• The Hubble time inferred from 10 time-delay lenses
• An optical time delay for the double gravitational lens system FBQ 0951+2635
• COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses V. The time delay in SDSS J1650+4251

Cited by in corpus (25)

• Gravitational Lens Time Delays: A Statistical Assessment of Lens Model Dependences and Implications for the Global Hubble Constant
• 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
• A Study of Gravitational Lens Chromaticity using Ground-based Narrow Band Photometry
• 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
• Lens Galaxy Properties of SBS1520+530: Insights from Keck Spectroscopy and AO Imaging
• 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
• H0LiCOW VI. Testing the fidelity of lensed quasar host galaxy reconstruction
• Microlensing of the broad emission lines in 27 gravitationally lensed quasars. Broad line region structure and kinematics
• 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
• 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
• 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
• Strongly Lensed Jets, Time Delays, and the Value of H0
• Exploring the environment, magnetic fields, and feedback effects of massive high-redshift galaxies with [CII]
• 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