Intensity distribution function and statistical properties of fast radio bursts

摘要

Fast Radio Bursts(FRBs) are intense radio flashes from the sky that are characterized by millisecond durations and Jansky-level flux densities. We carried out a statistical analysis on FRBs that have been discovered. Their mean dispersion measure, after subtracting the contribution from the interstellar medium of our Galaxy, is found to be ~ 660 pc cm^(-3), supporting their being from a cosmological origin. Their energy released in the radio band spans about two orders of magnitude, with a mean value of ~ 10^(39) erg. More interestingly, although the study of FRBs is still in a very early phase, the published collection of FRBs enables us to derive a useful intensity distribution function. For the 16 non-repeating FRBs detected by the Parkes telescope and the Green Bank Telescope, the intensity distribution can be described as d N/d F_(obs) =(4.1 ± 1.3) × 10~3F_(obs)^(-1.1±0.2) sky^(-1)d^(-1), where Fobs is the observed radio fluence in units of Jy ms. Here the power-law index is significantly flatter than the expected value of2.5 for standard candles distributed homogeneously in a flat Euclidean space. Based on this intensity distribution function, the Five-hundred-meter Aperture Spherical radio Telescope(FAST) is predicted to be able to detect about five FRBs for every 1000 h of observation time.