Response approach to the integrated shear 3-point correlation function: the impact of baryonic effects on small scales

Jan 14, 2022
15 pages
Published in:
  • Mon.Not.Roy.Astron.Soc. 515 (2022) 3, 4639-4654
  • Published: Aug 16, 2022
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Abstract: (Oxford University Press)
The integrated shear 3-point correlation function ζ_± is a higher-order statistic of the cosmic shear field that describes the modulation of the 2-point correlation function ξ_± by long-wavelength features in the field. Here, we introduce a new theoretical model to calculate ζ_± that is accurate on small angular scales, and that allows to take baryonic feedback effects into account. Our model builds on the realization that the small-scale ζ_± is dominated by the non-linear matter bispectrum in the squeezed limit, which can be evaluated accurately using the non-linear matter power spectrum and its first-order response functions to density and tidal field perturbations. We demonstrate the accuracy of our model by showing that it reproduces the small-scale ζ_± measured in simulated cosmic shear maps. The impact of baryonic feedback enters effectively only through the corresponding impact on the non-linear matter power spectrum, thereby permitting to account for these astrophysical effects on ζ_± similarly to how they are currently accounted for on ξ_±. Using a simple idealized Fisher matrix forecast for a DES-like survey we find that, compared to ξ_±, a combined |ξ± & ζ±\xi _{\pm }\ \&\ \zeta _{\pm }| analysis can lead to improvements of order |20 ⁣ ⁣40 per cent20\!-\!40{{\ \rm per\ cent}}| on the constraints of cosmological parameters such as σ_8 or the dark energy equation of state parameter w_0. We find similar levels of improvement on the constraints of the baryonic feedback parameters, which strengthens the prospects for cosmic shear data to obtain tight constraints not only on cosmology but also on astrophysical feedback models. These encouraging results motivate future works on the integrated shear 3-point correlation function towards applications to real survey data.
Note:
  • 15 pages, 9 figures; v2 matches the published version in MNRAS
  • gravitational lensing: weak
  • methods: analytical
  • cosmological parameters
  • large-scale structure of Universe