PIRSA:18090034

Uncovering the nature of dark matter with stellar streams in the Milky Way

Bonaca, A. (2018). Uncovering the nature of dark matter with stellar streams in the Milky Way. Perimeter Institute. https://pirsa.org/18090034

Bonaca, Ana. Uncovering the nature of dark matter with stellar streams in the Milky Way. Perimeter Institute, Sep. 25, 2018, https://pirsa.org/18090034 

          @misc{ pirsa_PIRSA:18090034,
            doi = {10.48660/18090034},
            url = {https://pirsa.org/18090034},
            author = {Bonaca, Ana},
            keywords = {Cosmology},
            language = {en},
            title = {Uncovering the nature of dark matter with stellar streams in the Milky Way},
            publisher = {Perimeter Institute},
            year = {2018},
            month = {sep},
            note = {PIRSA:18090034 see, \url{https://pirsa.org}}
          }

Ana Bonaca Carnegie Institution for Science

DOI 10.48660/18090034
Collection
Talk Type Scientific Series
Subject

Abstract

Stars orbiting in the halo of our galaxy, the Milky Way, are a window into the distribution of dark matter. In particular, tidally disrupted star clusters, which produce thin stellar streams, are optimal tracers of matter. Based on a Fisher-information calculation, we expect that the current data on the known Milky Way streams should constrain the radial profile and the shape of the inner halo to a precision of a few percent. In addition, stellar streams retain a detailed record of the matter field on small scales. Typically, streams are very thin -- approximately 100 times longer than they are wide, so even small gravitational perturbations introduce observable variations in the density of stars along the stream. Recently, significant gaps were detected in the GD-1 stellar stream, as well as stream stars displaced from the main stream. The observed structure is naturally reproduced in simulations where a stream like GD-1 encounters a massive perturber. None of the known Milky Way satellites has recently crossed paths with GD-1. If confirmed, the encounter scenario indicates the presence of an unknown, massive (~10^7 Msun) and compact (~<10 pc) object in the Milky Way -- the first evidence of dark substructure in a galactic halo.