CFHTLenS: weak lensing constraints on the ellipticity of galaxy-scale matter haloes and the galaxy-halo misalignment

Tim Schrabback, Stefan Hilbert, Henk Hoekstra, Patrick Simon, Edo van Uitert, Thomas Erben, Catherine Heymans, Hendrik Hildebrandt, Thomas D. Kitching, Yannick Mellier, Lance Miller, Ludovic Van Waerbeke, Philip Bett, Jean Coupon, Liping Fu, Michael J. Hudson, Benjamin Joachimi, Martin Kilbinger, Konrad Kuijken

Research output: Contribution to journalArticlepeer-review

Abstract

We present weak lensing constraints on the ellipticity of galaxy-scale matter haloes and the galaxy-halo misalignment. Using data from the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS), we measure the weighted-average ratio of the aligned projected ellipticity components of galaxy matter haloes and their embedded galaxies, fh, split by galaxy type. We then compare our observations to measurements taken from the Millennium Simulation, assuming different models of galaxy-halo misalignment. Using the Millennium Simulation, we verify that the statistical estimator used removes contamination from cosmic shear. We also detect an additional signal in the simulation, which we interpret as the impact of intrinsic shape-shear alignments between the lenses and their large-scale structure environment. These alignments are likely to have caused some of the previous observational constraints on fh to be biased high. From CFHTLenS, we find fh = -0.04 ± 0.25 for early-type galaxies, which is consistent with current models for the galaxy-halo misalignment predicting fh ≃ 0.20. For late-type galaxies we measure f_h=0.69_{-0.36}^{+0.37} from CFHTLenS. This can be compared to the simulated results which yield fh ≃ 0.02 for misaligned late-type models.
Original languageEnglish
Pages (from-to)1432-1452
JournalMonthly Notices of the Royal Astronomical Society
Volume454
Issue number2
DOIs
Publication statusPublished - 1 Dec 2015

Keywords

  • gravitational lensing: weak
  • galaxies: haloes

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