The Outer Stellar Mass of Massive Galaxies: A Simple Tracer of Halo Mass with Scatter Comparable to Richness and Reduced Projection Effects

Using the weak gravitational lensing data from the Hyper Suprime-Cam Subaru Strategic Program (HSC survey), we study the potential of different stellar mass estimates in tracing halo mass. We consider galaxies with $\log {M_{\star}/M_{\odot}}>11.5$ at 0.2 14.0$ and could be a better halo mass tracer at lower halo masses. Finally, using N-body simulations, we find that the lensing profiles of massive halos selected by M*[50,100] are consistent with the expectation for a sample without projection or mis-centering effects. On the other hand, Richness-selected clusters display an excess at R~1 Mpc in their lensing profiles, which may suggest a more significant impact from selection biases. These results suggest that Mstar-based tracers have distinct advantages in identifying massive halos, which could open up new avenues for cluster cosmology.