Abstract

Contributed Talk - Splinter JungeAG

Tuesday, 16 September 2025, 16:10

Timing Argument and Binary Motion of Local Group Galaxy Pairs

Yinbo Huang, Dr. Noam Libeskind, Dr. David Benisty
Leibniz-Institut für Astrophysik Potsdam (AIP)

The classical Timing Argument (TA) is still widely used to estimate the mass of the Local Group (LG), but its assumptions and its sensitivity to transverse velocity data deserve to be revisited in the light of modern cosmological simulations and GAIA DR3 observations. In this study, we analyze more than one million LG analogs extracted from AbacusSummit simulations and compute TA-based mass distributions and bindin probabilities using three different transverse velocity (Vt) inputs. We uncover the sensitivity of the model to velocity uncertainties. To validate and compare with other mass estimation methods, we selected LG analogs from TNG300-1 and applied the projected mass estimation method (PME), yielding a systematic overestimation corrected by Bayesian analysis. Insights are gained into the dynamical bounds of the LG under different analog selection criteria. This study reveals key biases in conventional LG mass estimates and proposes a physically based correction method.