Magnetic reconnection in solar flares can efficiently generate non-thermal electron beams. The accelerated electrons can, in turn, cause radio waves through kinetic instabilities as they propagate through the ambient plasma. We aim at investigating the wave emission caused by fast electron beams (FEBs) with characteristic non-thermal electron velocity distribution functions (EVDFs) generated by kinetic magnetic reconnection: bump-on-tail EVDFs along the separatrices and in the diffusion region, and perpendicular crescent-shaped EVDFs close to the diffusion region. For this sake we utilized 2.5D fully kinetic Particle-In-Cell (PIC) code simulations in this study. We found that: (1) the bump-on-tail EVDFs are unstable to cause electrostatic Langmuir waves via bump-on-tail instabilities and then multiple harmonic transverse waves from the diffusion region and the separatrices of reconnection. (2) The perpendicular crescent-shaped EVDFs, on the other hand, can cause multi-harmonic electromagnetic electron cyclotron waves through electron cyclotron maser instabilities in diffusion region of reconnection. Our results are applicable to diagnose the plasma parameters which control reconnection in solar flares by means of radio waves observations.
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