The Orphan-Chenab stream in the deformed halos of Milky Way and Large Magellanic Cloud

Abstract

Stellar streams have been used for a long time to constrain the mass and shape of the dark matter halo of the Milky Way (MW). Orphan-Chenab (OC) passes close to the Large Magellanic Cloud (LMC) during the LMC’s recent close passage to the MW. Modelling the OC stream requires at least including the mass of the LMC and the reflex motion of the MW. Still, the resulting inferred MW halo is flattened and aligned with the orbital plane or the present-day location of the LMC. The OC stream might be affected by passing through the deforming halos of the MW or the LMC. In this talk, I will present first results on modelling the OC stream in a time-dependent potential. This potential uses basis function expansions of N-body simulations of the MW-LMC passage. I will show differences in the stream properties when evolving in a rigid and live potential and disentangle which galaxy and which moments have the most prominent effects. This method will determine how well we can approximate the Galaxy’s halo using rigid potentials. We find that the OC stream is primarily sensitive to the deformation of the LMC, which is a promising first step to prove the dark matter halos’ time-dependence using stellar streams.

Sophia Lilleengen

Postdoctoral Researcher

I am interested how stellar streams are affected by time-dependent dark matter halos.