Short-lived mediators are often used to describe dark matter interactions with Standard Model particles .
When the dark matter mass is heavier than the mass of the mediator , it may self-annihilate into short-lived mediators , and in some cases this might be the dominant annihilation channel .
This scenario is known as secluded dark matter .
We use Fermi-LAT observations of dwarf spheroidal galaxies , H.E.S.S .
data from the Galactic center , and Planck measurements of the Cosmic Microwave Background to constrain secluded dark matter .
We explore the interplay between these experiments and we assess the impact of the mediator mass on our bounds , an often overlooked yet very important point .
In particular , we exclude pair -annihilation cross-sections greater or on the order of \sigma v \sim 4 \times 10 ^ { -27 } { cm ^ { 3 } / s } for dark matter masses around 10 GeV and greater or on the order of \sigma v \sim \times 10 ^ { -25 } { cm ^ { 3 } / s } for dark matter masses around a TeV .
Our findings supersede previous constraints which use Fermi-LAT data , and constitute the first limits on secluded dark sectors using the H.E.S.S .
telescope .
We also show that one can fit TeV gamma-ray observations from H.E.S.S .
with secluded dark matter annihilations , with the mediator mass impacting the best-fit dark matter particle mass .
Our findings indicate that any assessment of secluded dark sectors in the context of indirect detection significantly depends on the choice of the mediator mass .