Lensing is low: cosmology, galaxy formation or new physics?

Alexie Leauthaud, Shun Saito, Stefan Hilbert, Alexandre Barreira, Surhud More, Martin White, Shadab Alam, Peter Behroozi, Kevin Bundy, Jean Coupon, Thomas Erben, Catherine Heymans, Hendrik Hildebrandt, Rachel Mandelbaum, Lance Miller, Bruno Moraes, Maria E. S. Pereira, Sergio A. Rodríguez-Torres, Fabian Schmidt, Huan-Yuan ShanMatteo Viel, Francisco Villaescusa-Navarro

Research output: Contribution to journalArticlepeer-review


We present high signal-to-noise galaxy-galaxy lensing measurements of the Baryon Oscillation Spectroscopic Survey constant mass (CMASS) sample using 250 deg2 of weak-lensing data from Canada-France-Hawaii Telescope Lensing Survey and Canada-France-Hawaii Telescope Stripe 82 Survey. We compare this signal with predictions from mock catalogues trained to match observables including the stellar mass function and the projected and two-dimensional clustering of CMASS. We show that the clustering of CMASS, together with standard models of the galaxy-halo connection, robustly predicts a lensing signal that is 20-40 per cent larger than observed. Detailed tests show that our results are robust to a variety of systematic effects. Lowering the value of S_8=σ _8 \sqrt{Ω _m/0.3} compared to Planck Collaboration XIII reconciles the lensing with clustering. However, given the scale of our measurement (r <10 h-1 Mpc), other effects may also be at play and need to be taken into consideration. We explore the impact of baryon physics, assembly bias, massive neutrinos and modifications to general relativity on ΔΣ and show that several of these effects may be non-negligible given the precision of our measurement. Disentangling cosmological effects from the details of the galaxy-halo connection, the effect of baryons, and massive neutrinos, is the next challenge facing joint lensing and clustering analyses. This is especially true in the context of large galaxy samples from Baryon Acoustic Oscillation surveys with precise measurements but complex selection functions.
Original languageEnglish
Pages (from-to)3024-3047
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
Publication statusPublished - 3 Feb 2017


  • gravitational lensing: weak
  • cosmology: observations
  • large-scale structure of Universe


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