It sounds like you are referring to a hypothetical elementary particle that is proposed to be a component of dark matter. In many models of dark matter, particles like "WIMPs" (Weakly Interacting Massive Particles) or "axions" are considered as candidates. These particles could, indeed, emit certain particles or radiation when they undergo specific reactions or interactions.
For example, if we are discussing WIMPs, they might annihilate each other under certain conditions and produce photons or other particles like neutrinos. Axions, on the other hand, may be produced in various astrophysical processes and could interact with photons, leading to the emission of light under certain conditions.
If you have a specific name for the new elementary particle you are thinking of, please provide that, and I can offer more detailed information!