The imprint of $f(R)$ gravity on weak gravitational lensing I: Connection between observables and large scale structure

TL;DR

This paper investigates how $f(R)$ gravity influences weak gravitational lensing signals and large-scale structures, using simulations to identify potential observational signatures that could distinguish it from standard cosmology.

Contribution

It provides a detailed analysis of weak lensing observables and peak statistics in $f(R)$ gravity, highlighting promising methods to constrain the model with upcoming surveys.

Findings

Dark matter halo lensing signals differ by less than 10% between $f(R)$ and $ ext{Lambda CDM}$ for $|f_{R0}| \,\sim 10^{-5}$.

Troughs in the projected mass distribution are promising for constraining $f(R)$ models.

Including local minima in lensing maps enhances the ability to detect $f(R)$ effects.

Abstract

We study the effect of $f(R)$ gravity on the statistical properties of various large-scale structures which can be probed in weak gravitational lensing measurements. A set of ray-tracing simulations of gravitational lensing in $f(R)$ gravity enables us to explore cosmological information on (i) stacking analyses of weak lensing observables and (ii) peak statistics in reconstructed lensing mass maps. For the $f(R)$ model proposed by Hu \& Sawicki, the measured lensing signals of dark matter haloes in the stacking analysis would show a $\simlt10\%$ difference between the standard $\Lambda$CDM and the $f(R)$ model when the additional degree of freedom in $f(R)$ model would be $|f_{\rm R0}|\sim10^{-5}$. Among various large-scale structures to be studied in stacking analysis, troughs, i.e, underdensity regions in projected plane of foreground massive haloes, could be promising to constrain the model with $|f_{\rm R0}|\sim10^{-5}$, while stacking analysis around voids is found to be difficult to improve the constraint of $|f_{\rm R0}|$ even in future lensing surveys with a sky coverage of $\sim1000$ square degrees. On the peak statistics, we confirm the correspondence between local maxima and dark matter haloes along the line of sight, regardless of the modification of gravity in our simulation. Thus, the number count of high significance local maxima would be useful to probe the mass function of dark matter haloes even in the $f(R)$ model with $|f_{\rm R0}|\simlt10^{-5}$. We also find that including local minima in lensing mass maps would be helpful to improve the constant on $f(R)$ gravity down to $|f_{\rm R0}|=10^{-5}$ in ongoing weak lensing surveys.