Significant impact of Galactic dark matter particles on annihilation signals from Sagittarius analogues
arxiv(2024)
摘要
We examine the gamma-ray signal from dark matter (DM) annihilation from
analogues of the Sagittarius (Sgr) dwarf spheroidal galaxy in the Auriga
cosmological simulations. For velocity-dependent annihilation cross sections,
we compute emissions from simulated Sgr subhalos and from the Milky Way (MW)
foreground. In addition to the annihilation signals from DM particles bound to
Sgr, we consider for the first time the annihilation of DM particles bound to
the MW that overlap spatially with Sgr. For p-wave models this contribution can
enhance the signal by over an order of magnitude, while for d-wave models the
enhancement can be over two orders of magnitude. For Sommerfeld models, the
corresponding emission decreases by up to nearly an order of magnitude. For
Sommerfeld and s-wave models, the Sgr source can be visible above the MW
foreground emission, while for p and d-wave models, the signal towards Sgr is
most likely dominated by foreground MW emission. We interpret our results
within the context of the observed gamma-ray emission from Sgr, finding that
the templates from simulations likely have spatial morphology that is too
extended to explain the point-like emission that is observed.
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