Astrolunch: Khyati Malhan (Stockholm)

Tue, 23/06/2020 - 12:30 to 13:30

Title: Probing the nature of dark matter with accreted globular cluster streams
Abstract: Constraining the central mass density profiles of dark matter (DM) in low-mass galaxy halos (such as dwarf galaxies) is a potentially powerful test of our current cosmological model. Conventionally, these measurements in dwarf galaxies are based on Jeans equation (that require 3D velocity information for the tracer objects). However, most of the dwarfs are too far away from us to obtain accurate tangential motions for their stars. Without accurate tangential velocities, and with only line-of-sight velocities, stellar dynamical measurements of the DM density profiles are limited by the well known ``mass-anisotropy degeneracy''. Therefore, finding novel ways to probe the central DM densities of low-mass galaxy halos is important. The talk presents one of such novel schemes to probe DM in galaxy subhalos using ``stellar streams''.
In particular, I will be talking about "accreted" stellar streams- those produced from globular clusters that initially evolved within dwarf galaxies and later merged onto the Milky Way. I will discuss that the present day morphological and dynamical properties of such accreted streams can essentially be used to probe the central DM density profile (cusp/core scenarios) of their parent dwarf galaxies. In summary, a first study of MW streams "GD-1" and "Jhelum" indicates a preference for "cored" subhalos in their parent dwarfs. In general, the talk will present some of the recent efforts being made both in the observational (using ESA/Gaia data) and simulation realm to test new means to probe the central density profiles of galaxy subhalos using stellar streams.