The MillenniumTNG Project: the Impact of Baryons and Massive Neutrinos on High-Resolution Weak Gravitational Lensing Convergence Maps

We study weak gravitational lensing convergence maps produced from theMillenniumTNG (MTNG) simulations by direct projection of the mass distributionon the past backwards lightcone of a fiducial observer. We explore the lensingmaps over a large dynamic range in simulation mass and angular resolution,allowing us to establish a clear assessment of numerical convergence. Bycomparing full physics hydrodynamical simulations with correspondingdark-matter-only runs we quantify the impact of baryonic physics on the mostimportant weak lensing statistics. Likewise, we predict the impact of massiveneutrinos reliably far into the non-linear regime. We also demonstrate that the"fixed paired" variance suppression technique increases the statisticalrobustness of the simulation predictions on large scales not only for timeslices but also for continuously output lightcone data. We find that bothbaryonic and neutrino effects substantially impact weak lensing shearmeasurements, with the latter dominating over the former on large angularscales. Thus, both effects must explicitly be included to obtain sufficientlyaccurate predictions for stage IV lensing surveys. Reassuringly, our resultsagree accurately with other simulation results where available, supporting thepromise of simulation modelling for precision cosmology far into the non-linearregime.