Dark Matter from Dark Sectors - Self Interactions & Beyond

I will discuss some phenomenological consequences of extensions of the Standard Model containing a mediator lighter than the Dark Matter.A first example is that of DM self interactions, as a solution to putative discrepancies between collisionless cold DM and observations of galactic structures.I will show how this possibility is in tension with indirect detection constraints (from the CMB, gamma-rays and antiprotons), and what are the challenges to evade them via the introduction of an asymmetry in the DM population.A second example is that of dilution of the DM abundance via late decays of the mediator, that allows to evade the so-called unitarity bound.This enriches the physics case of several ongoing and planned telescopes (HESSII, HAWC, CTA, ANTARES, IceCube, KM3NeT, CALET,...) observing cosmic rays at and beyond 100 TeV