The effect of baryon cooling on the statistics of giant arcs and multiple quasars

TL;DR

This paper introduces a method to incorporate baryon cooling effects into dark matter simulations, showing it significantly increases the predicted frequency of giant arcs and lensed quasars, aligning better with observations.

Contribution

It provides a new recipe for including baryon cooling in dark matter simulations, improving the accuracy of lensing statistics predictions.

Findings

Baryon correction increases giant arc and quasar lensing frequency by ~25%.

Including baryons slightly raises the fraction of quadruple images.

Baryon effects are significant on scales of 10 arcsec and smaller.

Abstract

The statistics of giant arcs and large separation lensed quasars provide powerful constraints for the parameters of the underlying cosmological model. So far, most investigations have been carried out using pure dark matter simulations. Here we present a recipe for including the effects of baryon cooling (i.e. large galaxy formation) in dark matter N-body simulations that is consistent with observations of massive galaxies. Then we quantitatively compare lensing with and without applying this baryon correction to the pure dark matter case. Including the baryon correction significantly increases the frequency of giant arcs and lensed quasars, particularly on scales of 10 arcsec and smaller: the overall frequency of multiple images increases by about 25% for source redshifts between z_s = 1.5 and 7.5 and splittings larger than about 3 arcsec. The baryon rearrangement also slightly increases the fraction of quadruple images over doubles.