Search for decaying heavy dark matter in an effective interaction framework: a comparison of $γ$-ray and radio observations

Abstract

We investigate and compare the possibilities of observing decaying dark matter (DM) in γ-ray and radio telescopes. The special emphasise of the study is on a scalar heavy DM particle with mass in the trans-TeV range. DM decays, consistent with existing limits on the life time, are assumed to be driven by higher dimensional effective operators. We consider both two-body decays of a scalar dark particle and a dark sector having threebody decays, producing two standard model particles. It is found that the Fermi-LAT data on isotropic γ-ray background provides the best constraints so far, although the CTA telescope may be more effective for decays where one or two photons are directly produced. In all cases, deeper probes of the effective operators are possible in the upcoming SKA radio telescope with a few hundred hours of observation, using the radio synchrotron flux coming from energetic electrons produced in the decay cascades within dwarf spheroidal galaxies. Finally, we estimate how the SKA can constrain the parameter space spanned by the galactic magnetic field and the diffusion coefficient, if observations consistent with γ-ray data actually take place.

Constraints on MeV dark matter and primordial black holes: Inverse Compton signals at the SKA

“…Studies of the particle nature of DM using SKA are based on its annihilation and decay properties [29,33]. These annihilations or decays inside a dSph or galaxy cluster produce charged particles like electrons/positrons or neutral particles like photons.…”

“…The synchrotron flux, produced from GeV (or TeV) DM particles in any dSph or galaxy cluster, appears as a radio signal. Some previous works have studied this effect to constrain the GeV (or TeV) scale DM particles in the context of upcoming radio observations at the SKA [28,29,[31][32][33]. Nevertheless, it is difficult to detect the synchrotron flux in any radio telescope including the SKA if the DM particle mass reaches the MeV range.…”

“…While interactions with energetic CMB photons and other more energetic components of the bath such as infrared (IR) and starlight (SL) lead to X-ray and soft γ-ray emissions [26,27], scattering on the low-energy part of the CMB photon distribution can give rise to comparatively low frequency signals. Our aim is to study the possibility of detecting such low frequency signals with the upcoming radio telescope Square kilometer Array (SKA), which has been studied previously in the context of DM searches [28][29][30][31][32][33].…”

“…To this point, galactic and extragalactic synchrotron fluxes have been studied using current and upcoming radio telescopes, which appear to be more effective in the case of annihilation or decay of heavier DM particles [29,[31][32][33][34][35][36][37]. However, this method starts losing sensitivity (even for electron-positron dominated annihilations or decays) if masses of DM particles become < ∼ a GeV.…”