Size matters: the non-universal density profile of subhaloes in SPH simulations and implications for the Milky Way%26apos;s dSphs

作者：Di Cintio Arianna^*; Knebe Alexander; Libeskind Noam I; Brook Chris; Yepes Gustavo; Gottloeber Stefan; Hoffman Yehuda

来源：Monthly Notices of the Royal Astronomical Society, 2013, 431(2): 1220-1229.

DOI：10.1093/mnras/stt240

• methods: numerical
• galaxies: formation
• galaxies: haloes
• Local Group

We use dark matter only and full hydrodynamical Constrained Local Universe Simulations of the formation of the Local Group to study the density profile of subhaloes of the simulated Milky Way and Andromeda galaxies. We show that the Einasto model provides the best description of the subhaloes%26apos; density profile, as opposed to the more commonly used Navarro, Frenk %26 White profile or any generalization of it. We further find that the Einasto shape parameter n(E) is strongly correlated with the total subhalo mass, pointing towards the notion of a non-universality of the subhaloes%26apos; density profile. We observe that the effect of mass-loss due to tidal stripping, in both the dark matter only and the hydrodynamical run, is the reduction of the shape parameter n(E) between the infall and the present time. Assuming now that the dwarf spheroidals (dSphs) of our Galaxy follow the Einasto profile and using the maximum and minimum values of n(E) from our hydrodynamical simulation as a gauge, we can improve the observational constraints on the R-max-V-max pairs obtained for the brightest satellite galaxies of the Milky Way. When considering only the subhaloes with -13.2 %26lt;= M-V %26lt;= -8.8, i.e. the range of luminosity of the classical dwarfs, we find that all our simulated objects are consistent with the observed dSphs if their haloes follow the Einasto model with 1.6 %26lt;= n(E) %26lt;= 5.3. The numerically motivated Einasto profile for the observed dSphs will alleviate the recently presented %26apos;massive failures%26apos; problem.

• 出版日期2013-5