Correlation between TeV and X-ray bursts in Mrk 421

The TeV-X ray flare observed in May of 1994 in the BL Lac object Mrk 421 is interpreted in terms of synchrotron-self Compton (SSC) mechanism. It is su ggested that the TeV-X ray flare is produced by a high-energy component of flat electron-energy distribution with a spectral index of alpha(e) approxi mate to 0.25 at low energies. This flaring component is independent of the low-energy component (or quiescent component), which has a steeper electron -energy distribution and produces the radiation spectrum in the quiescent r egime. In addition to the fact that most radio outbursts show flat electron -energy distributions with spectral index alpha(e) approximate to 0.2-0.4, the above result implies that the basic mechanism of particle acceleration in AGNs produces flat energy distributions.