SKA-Phase 1 sensitivity for synchrotron radio emission from multi-TeV Dark Matter candidates

In the era of radio astronomy, the high sensitivity of the Square Kilometre Array (SKA) could play a decisive role in the detection of new radio sources. In particular, synchrotron radio emission from electrons and positrons produced by the annihilation of Weakly Interactive Massive Particles (WIMPs) in dark matter halos may be helpful in revealing the elusive nature of dark matter. In this work we study the SKA sensitivity for synchrotron radio emission from multi-TeV dark matter candidates annihilating in the Draco dwarf spheroidal galaxy. Firstly, we analyse the SKA sensitivity for model-independent dark matter. We show that the upper limit of detectability lies close to 10 TeV for $W^+W^-$, $\tau^+\tau^-$ and $t\overline{t}$ channels after 1000 hours. This limit is displaced to masses even higher than 100 TeV when the enhancement due to an intermediate massive black hole is considered. Secondly, we focus on some specific masses that may fit either the cut-off in the gamma-ray spectra observed by the High Energy Stereoscopic System (HESS) from the J1745-290 Galactic Centre source or the recent Alpha Magnetic Spectrometer (AMS)-02 positron fraction. Finally, we consider extra-dimensional brane-world theories whose fluctuations, dubbed branons, represent a natural candidate for WIMPs. In this specific scenario, we set constraints on the branons parameter space (f,M), being f the coupling of the branon to the Standard Model particles and M the mass of the branon itself. We conclude discussing prospective multiwavelength observation of multi-TeV dark matter signals.