Globular cluster

Physics

Cold dark matter

Sociology

Baryon

Dark matter

Halo

Population

Galaxy

Baryonic dark matter

Demography

Stars

Astrophysics

Dark matter halo

Milky Way

Monthly Notices of the Royal Astronomical Society

New data from the $\textit{Gaia}$ 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 analyze the stellar density perturbations in the GD-1 stream and show that they cannot be due to known baryonic structures like 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 $\approx 10^{7}$ to $10^9 \ M_{\rm{\odot}}$. We infer a total abundance of dark subhalos normalised to standard cold dark matter $n_{\rm sub}/n_{\rm sub, CDM} = 0.4 ^{+0.3}_{-0.2}$ ($68 \%$), which corresponds to a mass fraction contained in the subhalos $f_{\rm{sub}} = 0.14 ^{+0.11}_{-0.07} \%$, compatible with the predictions of hydrodynamical simulation of cold dark matter with baryons.

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

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