Stellar streams in the deforming halos of Milky Way and Large Magellanic Cloud

Abstract

Dark matter (DM) makes up most of the matter in the Universe, yet is only interacting via gravity and has not been detected yet. Our Galaxy, the Milky Way (MW) is a rich testbed for investigating DM predictions and constraining its nature. The MW is inside a DM halo that currently undergoes merger events with other galaxies, one of which is with the Large Magellanic Cloud (LMC). Stellar streams are groups of stars that fell into the Milky Way as smaller galaxies and then were disrupted in the DM halo. They are very sensitive to the amount of DM locally and are therefore used as tracers for the DM properties. Until now, the effect of the LMC was mostly ignored though and only recently included in models. The main effects of the LMC are the presence of a big amount of extra mass and the reaction of the MW to it. My research investigates a more subtle effect: the deformation of the DM halos of both galaxies. This is predicted by simulations but could not be observed yet. Stellar streams are expected to be sensitive to this deformation. In this talk, I will present novel results on modelling Chenab, a long stellar stream that has parts close to and far away from the LMC, in a deforming halo. I will show differences in the stream properties when evolving in a static and live potential. I will conclude with the Chenab stream being primarily sensitive to the deformation of the LMC, which is a promising first step to prove the dark matter halos’ deformation using stellar streams. This result will contribute to shaping the future of research in particle and astrophysics.

Sophia Lilleengen

Postdoctoral Researcher

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