Redshifts and lens profile for the double quasar QJ 0158-4325

C. Faure, T. Anguita, A. Eigenbrod, J. P. Kneib, V. Chantry, D. Alloin, N. Morgan, G. Covone

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)


Aims. We report on the redshift of the lensing galaxy and of the quasar QJ 0158-4325 and on the lens model of the system. Methods. A deep VLT/FORS2 spectrum and HST/NICMOS-F160W images are deconvolved. From the images we derive the light profile of the lensing galaxy and an accurate relative astrometry for the system. In addition we measure the flux ratio between the quasar images in the Mg II emission line to constrain the mass model. Results. From the spectrum we measure the redshift of the lensing galaxy (z = 0.317 ± 0.001) and of the quasar (z = 1.294 ± 0.008). Using the flux ratio in the lens model allows us to discard the SIE as a suitable approximation of the lens potential. On the contrary the truncated-PIEMD gives a good, fit to the lens and leads to a time delay of ΔtA-B = -14.5 ± 0.1 days, with H 0 = 73 km s-1 Mpc-1. Conclusions. Using the flux ratio to constrain the mass model favors the truncated-PIEMD over the SIE, while ignoring this constraint leaves the choice open.

Original languageEnglish
Pages (from-to)361-364
Number of pages4
JournalAstronomy and Astrophysics
Issue number2
Publication statusPublished - Mar 2009


  • Astrometry
  • Cosmology: Observations
  • Galaxies: Quasars: Individual: QJ 0158-4325
  • Gravitational lensing

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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