Evidence of a population of dark subhaloes from Gaia and Pan-STARRS observations of the GD-1 stream

Monday 6 Dec 2021, 13:30 → 13:50 Europe/Rome

0/0-3 - Sala Rosino (Dipartimento di Fisica e Astronomia - Edificio ex-Rizzato)

Speakers: Edoardo Borsato (Università degli Studi di Padova)

New data from the Gaia satellite, when combined with accurate photometry from the Pan-STARRS survey, allow us to accurately estimate the properties of the GD-1 stream. Here, we analyse the stellar density variations in the GD-1 stream and show that they cannot be due to known baryonic structures such as giant molecular clouds, globular clusters, or the Milky Way’s bar or spiral arms. A joint analysis of the GD-1 and Pal 5 streams instead requires a population of dark substructures with masses ≈107–109 M⊙⁠. We infer a total abundance of dark subhaloes normalized to standard cold dark matter nsub/nsub,CDM=0.4+0.3−0.2 (68 per cent), which corresponds to a mass fraction contained in the subhaloes fsub=0.14+0.11−0.07 per cent⁠, compatible with the predictions of hydrodynamical simulation of cold dark matter with baryons.

1911.02662.pdf

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