Universal dark halo scaling relation for the dwarf spheroidal satellites

Motivated by a recently found interesting property of the dark halo surface density within a radius, r_max giving the maximum circular velocity, V_max, we investigate it for dark halos of the Milky Way’s and Andromeda’s dwarf satellites based on cosmological simulations. We select and analyze the simulated subhalos associated with Milky Way-sized dark halos and find that the values of their surface densities are in good agreement with those for the observed dwarf spheroidal satellites even without employing any fitting procedures. This implies that this surface density would not be largely affected by any baryonic feedbacks and thus universal. Moreover, all subhalos on the small scales of dwarf satellites are expected to obey the universal relation, irrespective of differences in their orbital evolutions, host halo properties, and observed redshifts. In order to understand the origin of this universal dark halo relation. we also investigate orbital and dynamical evolutions of subhalos and find that most of subhalos evolve generally along the specific sequence, which is relation  between r_max and V_max,  even though these subhalos have undergone different histories of mass assembly and tidal stripping. This sequence, therefore, should be the key feature to understand the nature of the universal scaling relation.

Kohei Hayashi (KIAA/PKU)
KIAA first floor meeting room
Wed, 2017-03-15 12:00 to 13:00