Search of exoplanetary radio signals in the presence of strong interference: enhancing sensitivity by data accumulation

We develop a statistical approach aimed at the detection of weak sporadic pulses on the noise background. The results are applied to modeling the observational time series where pulsed radio emissions have to be recognized against the sky background fluctuations. The proposed methodology demonstrates the efficiency of using the statistics of peak values (integrated tail of probability distribution function of the intensity) for the purpose of signal detection. It is established that the highest sensitivity is reached with this method at low values of the filling factor (duty cycle) of the pulsed signals. If in addition the pulses have sufficiently high intensity, the discussed approach performs better than simple integration over the observational time. Then we discuss the possibility of detecting radio pulses from exoplanetary magnetospheres, especially from known “hot Jupiters” found by radial velocity measurements in the visible and we report our results from extensive observations of several candidate exoplanets with the world largest decameter telescope UTR-2. Although no detection of pulsed emission from exoplanets has been found to date, the analysis demonstrates the feasibility of detection with more stable receivers and longer observational time.