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Probing the Cosmological Principle with CMB lensing and cosmic shear

James Adam, Roy Maartens, Julien Larena, Chris Clarkson, Ruth Durrer

19/9/25 Published in : arXiv:2509.07259

The standard cosmological model assumes the Cosmological Principle. However, recent observations hint at possible violations of isotropy on large scales, possibly through late-time anisotropic expansion. Here we investigate the potential of cross-correlations between CMB lensing convergence \kappa and galaxy cosmic shear B-modes as a novel probe of such late-time anisotropies. Our signal-to-noise forecasts reveal that information from the \kappa-B cross-correlation is primarily contained on large angular scales (\ell \lesssim 200). We find that this cross-correlation for a Euclid-like galaxy survey is sensitive to anisotropy at the percent level. Making use of tomography yields a modest improvement of \sim 20\% in detection power. Incorporating the galaxy E-B cross-correlations would further enhance these constraints.

Entire article

Phase I & II research project(s)

  • String Theory
  • Field Theory

Phase III direction(s)

  • From Field Theory to Geometry and Topology

Gravitational Waves sourced by Gauge Fields during Inflation

Hecke modifications of conformal blocks outside the critical level

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The National Centres of Competence in Research (NCCRs) are a funding scheme of the Swiss National Science Foundation

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