Evidence of a population of dark subhalos from Gaia and Pan-STARRS observations of the GD-1 stream. (arXiv:1911.02662v2 [astro-ph.GA] UPDATED)

Evidence of a population of dark subhalos from Gaia and Pan-STARRS observations of the GD-1 stream. (arXiv:1911.02662v2 [astro-ph.GA] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Banik_N/0/1/0/all/0/1">Nilanjan Banik</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bovy_J/0/1/0/all/0/1">Jo Bovy</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bertone_G/0/1/0/all/0/1">Gianfranco Bertone</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Erkal_D/0/1/0/all/0/1">Denis Erkal</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Boer_T/0/1/0/all/0/1">T.J.L. de Boer</a>

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.

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.

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