Baryons, Neutrinos, Feedback and Weak Gravitational Lensing

Understand

(Abridged) The effect of baryonic feedback on the dark matter mass distribution is generally considered to be a nuisance to weak gravitational lensing.

• Measurements of cosmological parameters are affected as feedback alters the cosmic shear signal on angular scales smaller than a few arcminutes.
• Recent progress on the numerical modelling of baryon physics has shown that this effect could be so large that, rather than being a nuisance, the effect can be constrained with current weak lensing surveys, hence providing an alternative astrophysical insight on one of the most challenging questions of galaxy formation.
• In order to perform our analysis, we construct an analytic fitting formula that describes the effect of the baryons on the mass power spectrum.