Detection of Neutralino Annihilation Photons from External Galaxies
E. A. Baltz, C. Briot, P. Salati, R. Taillet, J. Silk
TL;DR
The paper addresses whether neutralino annihilation in dense extragalactic dark matter halos can yield gamma-ray signals detectable by atmospheric Cherenkov telescopes. It combines astrophysical density modeling for M87 and dwarf spheroidal galaxies with particle-physics inputs to compute the flux $\\Phi_{\\gamma}^{\\rm susy} = \\frac{1}{4\\pi} \\frac{\\langle \\sigma v \\rangle N_{\\gamma}}{m_{\\chi}^{2}} \\int_{\\rm los} \\rho_{\\chi}^{2} ds$ and the per-annihilation photon yield via Pythia, projecting the signal as $\\mu_{\\gamma}^{\\rm susy} = \\Phi_{\\gamma}^{\\rm susy} A_{\\rm eff} T$. The results indicate that, under plausible clumpy DM scenarios, portions of the SUSY parameter space produce observable gamma-ray fluxes with next-generation ACTs for both M87 and the dSphs, with the signal strongest in the central regions and depending on angular resolution. This work provides a practical framework for interpreting future ACT data in terms of supersymmetric DM models and highlights the role of substructure in boosting detectability.
Abstract
We consider neutralino annihilation in dense extragalactic systems known to be dominated by dark matter, in particular M87 and several local dwarf spheroidal galaxies. These annihilations can produce energetic gamma rays which may be visible to atmospheric Cerenkov telescopes. We explore the supersymmetric parameter space, and compute the expected flux of gamma--rays coming from these objects. It is shown that some parts of the parameter space lead to a signal observable with the next generation of Cerenkov telescopes, provided the supersymmetric dark matter has a clumpy structure, as may be expected in a hierarchical scenario for structure formation.