Local Group timing argument and virial theorem mass estimators from cosmological simulations

We identify Local Group (LG) analogs in the IllustrisTNG cosmological simulation, and use these to study two mass estimators for LG: one based on timing argument (TA) virial theorem (VT). Including updated measurements of Milky Way-M31 tangential velocity constant, we show that TA estimator slightly overestimates true median LG-mass, though ratio is consistent at approximate 90\% c.l. These are broad agreement with previous results using dark matter-only simulations. VT better estimates there a larger scatter relative corresponding TA. attribute broader several factors, including predominantly radial orbits LG satellite galaxies, which differs from assumption isotropic orbits. With systematic uncertainties derive, $4.75_{-2.41}^{+2.22} \times 10^{12}$ M$_\odot$ $2.0_{-1.5}^{+2.1} VT. consider LMC's effect estimates, do not find exact LMC-MW-M31 analogues Illustris However, simulations companions as massive LMC small, need further studies sample systems confirm results.