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The present work analyzes various aspects of M31 gamma-ray halo emission inits relation to annihilating dark matter (DM). The main aspect is the predictedeffect of asymmetry of the intensity of emission due to inverse Comptonscattering (ICS) of a possible population of relativistic electrons andpositrons ($e^\pm$) in the galactic halo on starlight photons. This asymmetryis expected to exist around the major galactic axis, and arises due toanisotropy of the interstellar radiation field and the inclination of M31. ICSemission and its asymmetry were modeled by GALPROP code for the trial case of$e^\pm$ generated by annihilating weakly interacting massive particles (WIMPs)with various properties. The asymmetry was obtained to appear at photonenergies above $\sim$ 0.1 MeV. Morphological and spectral properties of theasymmetry were studied in detail. Potential observational detection of theasymmetry may allow to infer the leptonic fraction in the emission generationmechanism, thus providing valuable inferences for understanding the nature ofM31 gamma-ray halo emission. Specific asymmetry predictions were made for therecently claimed DM interpretation of the outer halo emission. The paper alsostudied the role of secondary -- ICS and bremsstrahlung -- emissions due to DMannihilation for that interpretation. And, finally, the latter was shown to besomewhat restricted by the recently derived WIMP constraints from radio data onM31.

Nature of M31 gamma-ray halo in relation to dark matter annihilation