Probing dark matter models with novel gamma-ray features from cascade processes
Sergio López Gehler, Technische Universität München, Germany
Federico von der Pahlen, GFIF, U. Antioquia, Colombia
The gamma-ray sky is undergoing a meticulous scan done by several experiments hoping to find some hint of dark matter. A sharp feature nested in the otherwise smooth energy spectrum would be the cleanest way to tag data as dark matter tinted, helping us pinpoint the unknown properties of dark matter. Over the years a lot of attention has been paid to two specific features: monochromatic lines originated in dark matter annihilations into photons; and a hard bump at the kinematical end produced by internal bremsstrahlung photons. In this talk, I explore instead a third class of signatures: gamma-ray boxes and triangles, which are natural outputs of cascade processes involving short-lived intermediate states and photonic final states. No fine tuning or other strict assumptions are needed to produce a hard signature; however, the specific form of the spectrum varies with the properties of the involved particles, changing its width or its form (rectangular or triangular). I will discuss physical models capable of producing such signatures, and then present limits on the velocity-averaged cross section, using current data by H.E.S.S. and Fermi-LAT. Finally, I discuss the prospects for the future CTA experiment to discover or rule out dark matter models featuring gamma-ray boxes and triangles.