An HSC view of the CMASS galaxy sample. Halo mass as a function of stellar mass, size and Sérsic index

Abstract: Aims. We wish to determine the distribution of dark matter halo masses as a function of the stellar mass and the stellar mass profile, for massive galaxies in the BOSS CMASS sample. Methods. We use grizy photometry from HSC to obtain S\'ersic fits and stellar masses of CMASS galaxies for which HSC weak lensing data is available, visually selected to have spheroidal morphology. We apply a cut in stellar mass, $\log{M_/M_\odot} > 11.0$,selecting $\sim$10, 000 objects. Using a Bayesian hierarchical inference method, we first investigate the distribution of S\'ersic index and size as a function of stellar mass. Then, making use of shear measurements from HSC, we measure the distribution of halo mass as a function of stellar mass, size and S\'ersic index. Results. Our data reveals a steep stellar mass-size relation $R_e \propto M_^{\beta_R}$, with $\beta_R$ larger than unity, and a positive correlation between S\'ersic index and stellar mass: $n \propto M_*^{0.46}$. Halo mass scales approximately with the 1.7 power of the stellar mass. We do not find evidence for an additional dependence of halo mass on size or S\'ersic index at fixed stellar mass. Conclusions. Our results disfavour galaxy evolution models that predict significant differences in the size growth efficiency of galaxies living in low and high mass halos.