Weak-lensing study in VOICE survey - I. Shear measurement

Liping Fu, Dezi Liu, Mario Radovich, Xiangkun Liu, Chuzhong Pan, Zuhui Fan, Giovanni Covone, Mattia Vaccari, Valeria Amaro, Massimo Brescia, Massimo Capaccioli, Demetra De Cicco, Aniello Grado, Luca Limatola, Lance Miller, Nicola R. Napolitano, Maurizio Paolillo, Giuliano Pignata

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


The VST Optical Imaging of the CDFS and ES1 Fields (VOICE) Survey is a Guaranteed Time programme carried out with the European Southern Observatory (ESO) VLT Survey Telescope (VST) telescope to provide deep optical imaging over two 4 deg2 patches of the sky centred on the Chandra Deep Field South (CDFS) and ES1 as part of the ESO-Spitzer Imaging Extragalactic Survey. We present the cosmic shear measurement over the 4 deg2 covering the CDFS region in the r band using LensFit. Each of the four tiles of 1 deg2 has more than 100 exposures, of which more than 50 exposures passed a series of image quality selection criteria for weak-lensing study. The 5σ limiting magnitude in r band is 26.1 for point sources, which is ≳1 mag deeper than other weak-lensing survey in the literature [e.g. the Kilo Degree Survey (KiDS) at VST]. The photometric redshifts are estimated using the VOICE u, g, r, i together with near-infrared VIDEO data Y, J, H, Ks. The mean redshift of the shear catalogue is 0.87, considering the shear weight. The effective galaxy number density is 16.35 gal arcmin-2, which is nearly twice the one of KiDS. The performance of LensFit on such a deep data set was calibrated using VOICE-like mock image simulations. Furthermore, we have analysed the reliability of the shear catalogue by calculating the star-galaxy crosscorrelations, the tomographic shear correlations of two redshift bins and the contaminations of the blended galaxies. As a further sanity check, we have constrained cosmological parameters by exploring the parameter space with Population Monte Carlo sampling. For a flat Λ cold dark matter model, we have obtained Σ8 = σ8(Ωm/0.3)0.5 = 0.68+0.11 -0.15.

Original languageEnglish
Pages (from-to)3858-3872
Number of pages15
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
Publication statusPublished - 21 Sep 2018


  • Cosmology: observations
  • Gravitational lensing: weak
  • Methods: data analysis
  • Survey

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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