The SLUGGS survey: dark matter fractions at large radii and assembly epochs of early-type galaxies from globular cluster kinematics

摘要: We use globular cluster kinematics data, primarily from the SLUGGS survey, to measure dark matter fraction ($f_{\rm DM}$) and average density ($\left $) within inner 5 effective radii ($R_{\rm e}$) for 32 nearby early--type galaxies (ETGs) with stellar mass log $(M_*/\rm M_\odot)$ ranging $10.1$ $11.8$. compare our results a simple galaxy model based on scaling relations as well cosmological hydrodynamical simulations where profile has been modified through various physical processes. We find high $f_{\rm DM}$ ($\geq0.6$) 5~$R_{\rm e}$ in most of sample, which we interpret signature late assembly history that is largely devoid gas-rich major mergers. However, around $(M_*/M_\odot) \sim 11$, there wide range may be challenging explain any single model. tentative evidence lenticulars (S0s), unlike ellipticals, have distributions are similar spiral galaxies, decreasing luminosity increases. do not difference between $\left $ S0s ellipticals despite differences their populations. also used infer epoch halo ($z{\sim}2-4$). By comparing age central stars inferred formation, able gain more insight into histories. Our suggest fundamental dominant late-phase channel elliptical galaxies.